mirror of
https://github.com/torvalds/linux.git
synced 2026-09-19 00:58:02 +02:00
185a4caeec
384 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
2cbf335f8c |
Scheduler updates for v7.2:
SMP load-balancing updates:
- A large series to introduce infrastructure for cache-aware load
balancing, with the goal of co-locating tasks that share data
within the same Last Level Cache (LLC) domain. By improving cache
locality, the scheduler can reduce cache bouncing and cache misses,
ultimately improving data access efficiency.
Implemented by Chen Yu and Tim Chen, based on early prototype work
by Peter Zijlstra, with fixes by Jianyong Wu, Peter Zijlstra and
Shrikanth Hegde.
- A series to simplify CONFIG_SCHED_SMT ifdef usage (Shrikanth Hegde)
Fair scheduler updates:
- A series to improve SD_ASYM_CPUCAPACITY scheduling by introducing
SMT awareness (Andrea Righi, K Prateek Nayak)
- A series to optimize cfs_rq and sched_entity allocation for
better data locality (Zecheng Li)
- A preparatory series to change fair/cgroup scheduling to a single
runqueue, without the final change (Peter Zijlstra)
- Auto-manage ext/fair dl_server bandwidth (Andrea Righi)
- Fix cpu_util runnable_avg arithmetic (Hongyan Xia)
- Optimize update_tg_load_avg()'s rate-limiting code
(Rik van Riel)
- Allow account_cfs_rq_runtime() to throttle current hierarchy
(K Prateek Nayak)
- Update util_est after updating util_avg during dequeue, to fix
the util signal update logic, which reduces signal noise
(Vincent Guittot)
Scheduler topology updates:
- Allow multiple domains to claim sched_domain_shared (K Prateek Nayak)
- Add parameter to split LLC (Peter Zijlstra)
Core scheduler updates:
- Use trace_call__<tp>() to save a static branch (Gabriele Monaco)
Scheduler statistics updates:
- Drop now-stale mul_u64_u64_div_u64() cputime over-approximation guard
(Nicolas Pitre)
Deadline scheduler updates:
- Reject debugfs dl_server writes for offline CPUs (Andrea Righi)
- Fix replenishment logic for non-deferred servers
(Yuri Andriaccio)
RT scheduling updates:
- Turn RT_PUSH_IPI default off for non PREEMPT_RT (Steven Rostedt)
- Update default bandwidth for real-time tasks to 1.0
(Yuri Andriaccio)
Proxy scheduling updates:
- A series to implement Optimized Donor Migration for Proxy Execution
(John Stultz, Peter Zijlstra)
- Various proxy scheduling cleanups and fixes
(Peter Zijlstra, K Prateek Nayak)
Misc fixes, improvements and cleanups by Aaron Lu, Andrea Righi,
Zenghui Yu, Chen Yu, Guanyou.Chen, John Stultz, Shrikanth Hegde,
Peter Zijlstra, Liang Luo and Yiyang Chen.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=V3Wc
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"SMP load-balancing updates:
- A large series to introduce infrastructure for cache-aware load
balancing, with the goal of co-locating tasks that share data
within the same Last Level Cache (LLC) domain. By improving cache
locality, the scheduler can reduce cache bouncing and cache misses,
ultimately improving data access efficiency.
Implemented by Chen Yu and Tim Chen, based on early prototype work
by Peter Zijlstra, with fixes by Jianyong Wu, Peter Zijlstra and
Shrikanth Hegde.
- A series to simplify CONFIG_SCHED_SMT ifdef usage (Shrikanth Hegde)
Fair scheduler updates:
- A series to improve SD_ASYM_CPUCAPACITY scheduling by introducing
SMT awareness (Andrea Righi, K Prateek Nayak)
- A series to optimize cfs_rq and sched_entity allocation for better
data locality (Zecheng Li)
- A preparatory series to change fair/cgroup scheduling to a single
runqueue, without the final change (Peter Zijlstra)
- Auto-manage ext/fair dl_server bandwidth (Andrea Righi)
- Fix cpu_util runnable_avg arithmetic (Hongyan Xia)
- Optimize update_tg_load_avg()'s rate-limiting code (Rik van Riel)
- Allow account_cfs_rq_runtime() to throttle current hierarchy
(K Prateek Nayak)
- Update util_est after updating util_avg during dequeue, to fix the
util signal update logic, which reduces signal noise (Vincent
Guittot)
Scheduler topology updates:
- Allow multiple domains to claim sched_domain_shared (K Prateek
Nayak)
- Add parameter to split LLC (Peter Zijlstra)
Core scheduler updates:
- Use trace_call__<tp>() to save a static branch (Gabriele Monaco)
Scheduler statistics updates:
- Drop now-stale mul_u64_u64_div_u64() cputime over-approximation
guard (Nicolas Pitre)
Deadline scheduler updates:
- Reject debugfs dl_server writes for offline CPUs (Andrea Righi)
- Fix replenishment logic for non-deferred servers (Yuri Andriaccio)
RT scheduling updates:
- Turn RT_PUSH_IPI default off for non PREEMPT_RT (Steven Rostedt)
- Update default bandwidth for real-time tasks to 1.0 (Yuri
Andriaccio)
Proxy scheduling updates:
- A series to implement Optimized Donor Migration for Proxy Execution
(John Stultz, Peter Zijlstra)
- Various proxy scheduling cleanups and fixes (Peter Zijlstra,
K Prateek Nayak)
Misc fixes, improvements and cleanups by Aaron Lu, Andrea Righi,
Zenghui Yu, Chen Yu, Guanyou.Chen, John Stultz, Shrikanth Hegde,
Peter Zijlstra, Liang Luo and Yiyang Chen"
* tag 'sched-core-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (91 commits)
sched/fair: Fix newidle vs core-sched
sched/deadline: Use task_on_rq_migrating() helper
sched/core: Combine separate 'else' and 'if' statements
sched/fair: Fix cpu_util runnable_avg arithmetic
sched/fair: Unify cfs_rq throttling via account_cfs_rq_runtime()
sched/fair: Move the throttled tasks to a local list in tg_unthrottle_up()
sched/fair: Call update_curr() before unthrottling the hierarchy
sched/fair: Use throttled_csd_list for local unthrottle
sched/fair: Convert cfs bandwidth throttling to use guards
sched/fair: Allocate cfs_tg_state with percpu allocator
sched/fair: Remove task_group->se pointer array
sched/fair: Co-locate cfs_rq and sched_entity in cfs_tg_state
sched: restore timer_slack_ns when resetting RT policy on fork
MAINTAINERS: Fix spelling mistake in Peter's name
sched: Simplify ttwu_runnable()
sched/proxy: Remove superfluous clear_task_blocked_in()
sched/proxy: Remove PROXY_WAKING
sched/proxy: Switch proxy to use p->is_blocked
sched/proxy: Only return migrate when needed
sched: Be more strict about p->is_blocked
...
|
||
|
Liang Luo
|
9ebe5c3c29 |
sched/deadline: Use task_on_rq_migrating() helper
Replace the open-coded "p->on_rq == TASK_ON_RQ_MIGRATING" comparisons in enqueue_task_dl() and dequeue_task_dl() with the existing task_on_rq_migrating() helper, consistent with the rest of the scheduler code. No functional change. Signed-off-by: Liang Luo <luoliang@kylinos.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://patch.msgid.link/20260608075500.387271-1-luoliang@kylinos.cn |
||
|
John Stultz
|
cd8e62c858 |
sched: deadline: Add dl_rq->curr pointer to address issues with Proxy Exec
The DL scheduler keeps the current task in the rbtree, since the deadline value isn't usually chagned while the task is runnable. This results in set_next_task() and put_prev_task() being simpler, but unfortunately this causes complexity elsewhere. Specifically when update_curr_dl() updates the deadline, it has to dequeue and then enqueue the task. From put_prev_task_dl(), we first call update_curr_dl(), and then call enqueue_pushable_dl_task(). However, with Proxy Exec this goes awry. Since when a mutex is released, we might wake the waiting rq->donor. This will cause put_prev_task() to be called on the donor to take it off the cpu for return migration. At that point, from put_prev_task_dl() the update_curr_dl() logic will dequeue & enqueue the task, and the enqueue function will call enqueue_pushable_dl_task() (since the task_current() check won't prevent it). Then back up the callstack in put_prev_task_dl() we'll end up calling enqueue_pushable_dl_task() again, tripping the !RB_EMPTY_NODE(&p->pushable_dl_tasks) warning. So to avoid this, use Peter's suggested[1] approach, and add a dl_rq->curr pointer that is set/cleared from set_next_task()/ put_prev_task(), which effectively tracks the rq->donor. We can then use this to avoid adding the active donor to the pushable list from enqueue_task_dl(). [1]: https://lore.kernel.org/lkml/20260304095123.GP606826@noisy.programming.kicks-ass.net/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: John Stultz <jstultz@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260512025635.2840817-4-jstultz@google.com |
||
|
John Stultz
|
96a6988fb5 |
sched: deadline: Add some helper variables to cleanup deadline logic
As part of an improvement to handling pushable deadline tasks, Peter suggested this cleanup[1], to use helper values for dl_entity and dl_rq in the enqueue_task_dl() and put_prev_task_dl() functions. There should be no functional change from this patch. To make sure this cleanup change doesn't obscure later logic changes, I've split it into its own patch. [1]: https://lore.kernel.org/lkml/20260304095123.GP606826@noisy.programming.kicks-ass.net/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: John Stultz <jstultz@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260512025635.2840817-3-jstultz@google.com |
||
|
John Stultz
|
7a3a6bfbd6 |
sched: Rework prev_balance() to avoid stale prev references
Historically, the prev value from __schedule() was the rq->curr. This prev value is passed down through numerous functions, and used in the class scheduler implementations. The fact that prev was on_cpu until the end of __schedule(), meant it was stable across the rq lock drops that the class->balance() implementations often do. However, with proxy-exec, the prev passed to functions called by __schedule() is rq->donor, which may not be the same as rq->curr and may not be on_cpu, this makes the prev value potentially unstable across rq lock drops. A recently found issue with proxy-exec, is when we begin doing return migration from try_to_wake_up(), its possible we may be waking up the rq->donor. When we do this, we proxy_resched_idle() to put_prev_set_next() setting the rq->donor to rq->idle, allowing the rq->donor to be return migrated and allowed to run. This however runs into trouble, as on another cpu we might be in the middle of calling __schedule(). Conceptually the rq lock is held for the majority of the time, but in calling prev_balance() its possible the class->balance() handler call may briefly drop the rq lock. This opens a window for try_to_wake_up() to wake and return migrate the rq->donor before the class logic reacquires the rq lock. Unfortunately prev_balance() pass in a prev argument, to which we pass rq->donor. However this prev value can now become stale and incorrect across a rq lock drop. So, to correct this, rework the prev_balance() call so that it does not take a "prev" argument. Signed-off-by: John Stultz <jstultz@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260512025635.2840817-2-jstultz@google.com |
||
|
Andrea Righi
|
e7b63427fd |
sched_ext: Auto-register/unregister dl_server reservations
Commit
|
||
|
Yuri Andriaccio
|
eecd5e117c |
sched/deadline: Fix replenishment logic for non-deferred servers
Enqueue and replenish non-deferred deadline servers when their runtime is exhausted and the replenishment timer could not be started because it is too close to the wake-up instant. Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260430213835.62217-2-yurand2000@gmail.com |
||
|
Guopeng Zhang
|
5dd74441cb |
cgroup/cpuset: Reserve DL bandwidth only for root-domain moves
cpuset_can_attach() currently adds the bandwidth of all migrating
SCHED_DEADLINE tasks to sum_migrate_dl_bw. If the source and destination
cpuset effective CPU masks do not overlap, the whole sum is then
reserved in the destination root domain.
set_cpus_allowed_dl(), however, subtracts bandwidth from the source
root domain only when the affinity change really moves the task between
root domains. A DL task can move between cpusets that are still in the
same root domain, so including that task in sum_migrate_dl_bw can reserve
destination bandwidth without a matching source-side subtraction.
Share the root-domain move test with set_cpus_allowed_dl(). Keep
nr_migrate_dl_tasks counting all migrating deadline tasks for cpuset DL
task accounting, but add to sum_migrate_dl_bw only for tasks that need a
root-domain bandwidth move. Keep using the destination cpuset effective
CPU mask and leave the broader can_attach()/attach() transaction model
unchanged.
Fixes:
|
||
|
Linus Torvalds
|
fdbfee9fc5 |
Runtime Verification updates for 7.1:
- Refactor da_monitor header to share handlers across monitor types No functional changes, only less code duplication. - Add Hybrid Automata model class Add a new model class that extends deterministic automata by adding constraints on transitions and states. Those constraints can take into account wall-clock time and as such allow RV monitor to make assertions on real time. Add documentation and code generation scripts. - Add stall monitor as hybrid automaton example Add a monitor that triggers a violation when a task is stalling as an example of automaton working with real time variables. - Convert the opid monitor to a hybrid automaton The opid monitor can be heavily simplified if written as a hybrid automaton: instead of tracking preempt and interrupt enable/disable events, it can just run constraints on the preemption/interrupt states when events like wakeup and need_resched verify. - Add support for per-object monitors in DA/HA Allow writing deterministic and hybrid automata monitors for generic objects (e.g. any struct), by exploiting a hash table where objects are saved. This allows to track more than just tasks in RV. For instance it will be used to track deadline entities in deadline monitors. - Add deadline tracepoints and move some deadline utilities Prepare the ground for deadline monitors by defining events and exporting helpers. - Add nomiss deadline monitor Add first example of deadline monitor asserting all entities complete before their deadline. - Improve rvgen error handling Introduce AutomataError exception class and better handle expected exceptions while showing a backtrace for unexpected ones. - Improve python code quality in rvgen Refactor the rvgen generation scripts to align with python best practices: use f-strings instead of %, use len() instead of __len__(), remove semicolons, use context managers for file operations, fix whitespace violations, extract magic strings into constants, remove unused imports and methods. - Fix small bugs in rvgen The generator scripts presented some corner case bugs: logical error in validating what a correct dot file looks like, fix an isinstance() check, enforce a dot file has an initial state, fix type annotations and typos in comments. - rvgen refactoring Refactor automata.py to use iterator-based parsing and handle required arguments directly in argparse. - Allow epoll in rtapp-sleep monitor The epoll_wait call is now rt-friendly so it should be allowed in the sleep monitor as a valid sleep method. -----BEGIN PGP SIGNATURE----- iIoEABYKADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCad4kUxQccm9zdGVkdEBn b29kbWlzLm9yZwAKCRAp5XQQmuv6qiJgAPsGJ0TCTubdn2x6fpwLDKUcSsNsYrok m8gLHeK0rmkKNQD/ajUW+RBsOufXAsnSzUoUcl7sw1TSiQJ085U+0+ZeDgM= =WZqk -----END PGP SIGNATURE----- Merge tag 'trace-rv-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull runtime verification updates from Steven Rostedt: - Refactor da_monitor header to share handlers across monitor types No functional changes, only less code duplication. - Add Hybrid Automata model class Add a new model class that extends deterministic automata by adding constraints on transitions and states. Those constraints can take into account wall-clock time and as such allow RV monitor to make assertions on real time. Add documentation and code generation scripts. - Add stall monitor as hybrid automaton example Add a monitor that triggers a violation when a task is stalling as an example of automaton working with real time variables. - Convert the opid monitor to a hybrid automaton The opid monitor can be heavily simplified if written as a hybrid automaton: instead of tracking preempt and interrupt enable/disable events, it can just run constraints on the preemption/interrupt states when events like wakeup and need_resched verify. - Add support for per-object monitors in DA/HA Allow writing deterministic and hybrid automata monitors for generic objects (e.g. any struct), by exploiting a hash table where objects are saved. This allows to track more than just tasks in RV. For instance it will be used to track deadline entities in deadline monitors. - Add deadline tracepoints and move some deadline utilities Prepare the ground for deadline monitors by defining events and exporting helpers. - Add nomiss deadline monitor Add first example of deadline monitor asserting all entities complete before their deadline. - Improve rvgen error handling Introduce AutomataError exception class and better handle expected exceptions while showing a backtrace for unexpected ones. - Improve python code quality in rvgen Refactor the rvgen generation scripts to align with python best practices: use f-strings instead of %, use len() instead of __len__(), remove semicolons, use context managers for file operations, fix whitespace violations, extract magic strings into constants, remove unused imports and methods. - Fix small bugs in rvgen The generator scripts presented some corner case bugs: logical error in validating what a correct dot file looks like, fix an isinstance() check, enforce a dot file has an initial state, fix type annotations and typos in comments. - rvgen refactoring Refactor automata.py to use iterator-based parsing and handle required arguments directly in argparse. - Allow epoll in rtapp-sleep monitor The epoll_wait call is now rt-friendly so it should be allowed in the sleep monitor as a valid sleep method. * tag 'trace-rv-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (32 commits) rv: Allow epoll in rtapp-sleep monitor rv/rvgen: fix _fill_states() return type annotation rv/rvgen: fix unbound loop variable warning rv/rvgen: enforce presence of initial state rv/rvgen: extract node marker string to class constant rv/rvgen: fix isinstance check in Variable.expand() rv/rvgen: make monitor arguments required in rvgen rv/rvgen: remove unused __get_main_name method rv/rvgen: remove unused sys import from dot2c rv/rvgen: refactor automata.py to use iterator-based parsing rv/rvgen: use class constant for init marker rv/rvgen: fix DOT file validation logic error rv/rvgen: fix PEP 8 whitespace violations rv/rvgen: fix typos in automata and generator docstring and comments rv/rvgen: use context managers for file operations rv/rvgen: remove unnecessary semicolons rv/rvgen: replace __len__() calls with len() rv/rvgen: replace % string formatting with f-strings rv/rvgen: remove bare except clauses in generator rv/rvgen: introduce AutomataError exception class ... |
||
|
Linus Torvalds
|
1c3b68f0d5 |
Scheduler changes for v7.1:
Fair scheduling updates:
- Skip SCHED_IDLE rq for SCHED_IDLE tasks (Christian Loehle)
- Remove superfluous rcu_read_lock() in the wakeup path (K Prateek Nayak)
- Simplify the entry condition for update_idle_cpu_scan() (K Prateek Nayak)
- Simplify SIS_UTIL handling in select_idle_cpu() (K Prateek Nayak)
- Avoid overflow in enqueue_entity() (K Prateek Nayak)
- Update overutilized detection (Vincent Guittot)
- Prevent negative lag increase during delayed dequeue (Vincent Guittot)
- Clear buddies for preempt_short (Vincent Guittot)
- Implement more complex proportional newidle balance (Peter Zijlstra)
- Increase weight bits for avg_vruntime (Peter Zijlstra)
- Use full weight to __calc_delta() (Peter Zijlstra)
RT and DL scheduling updates:
- Fix incorrect schedstats for rt and dl thread (Dengjun Su)
- Skip group schedulable check with rt_group_sched=0 (Michal Koutný)
- Move group schedulability check to sched_rt_global_validate()
(Michal Koutný)
- Add reporting of runtime left & abs deadline to sched_getattr()
for DEADLINE tasks (Tommaso Cucinotta)
Scheduling topology updates by K Prateek Nayak:
- Compute sd_weight considering cpuset partitions
- Extract "imb_numa_nr" calculation into a separate helper
- Allocate per-CPU sched_domain_shared in s_data
- Switch to assigning "sd->shared" from s_data
- Remove sched_domain_shared allocation with sd_data
Energy-aware scheduling updates:
- Filter false overloaded_group case for EAS (Vincent Guittot)
- PM: EM: Switch to rcu_dereference_all() in wakeup path
(Dietmar Eggemann)
Infrastructure updates:
- Replace use of system_unbound_wq with system_dfl_wq (Marco Crivellari)
Proxy scheduling updates by John Stultz:
- Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
- Minimise repeated sched_proxy_exec() checking
- Fix potentially missing balancing with Proxy Exec
- Fix and improve task::blocked_on et al handling
- Add assert_balance_callbacks_empty() helper
- Add logic to zap balancing callbacks if we pick again
- Move attach_one_task() and attach_task() helpers to sched.h
- Handle blocked-waiter migration (and return migration)
- Add K Prateek Nayak to scheduler reviewers for proxy execution
Misc cleanups and fixes by John Stultz, Joseph Salisbury,
Peter Zijlstra, K Prateek Nayak, Michal Koutný, Randy Dunlap,
Shrikanth Hegde, Vincent Guittot, Zhan Xusheng, Xie Yuanbin
and Vincent Guittot.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=NjyS
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Fair scheduling updates:
- Skip SCHED_IDLE rq for SCHED_IDLE tasks (Christian Loehle)
- Remove superfluous rcu_read_lock() in the wakeup path (K Prateek Nayak)
- Simplify the entry condition for update_idle_cpu_scan() (K Prateek Nayak)
- Simplify SIS_UTIL handling in select_idle_cpu() (K Prateek Nayak)
- Avoid overflow in enqueue_entity() (K Prateek Nayak)
- Update overutilized detection (Vincent Guittot)
- Prevent negative lag increase during delayed dequeue (Vincent Guittot)
- Clear buddies for preempt_short (Vincent Guittot)
- Implement more complex proportional newidle balance (Peter Zijlstra)
- Increase weight bits for avg_vruntime (Peter Zijlstra)
- Use full weight to __calc_delta() (Peter Zijlstra)
RT and DL scheduling updates:
- Fix incorrect schedstats for rt and dl thread (Dengjun Su)
- Skip group schedulable check with rt_group_sched=0 (Michal Koutný)
- Move group schedulability check to sched_rt_global_validate()
(Michal Koutný)
- Add reporting of runtime left & abs deadline to sched_getattr()
for DEADLINE tasks (Tommaso Cucinotta)
Scheduling topology updates by K Prateek Nayak:
- Compute sd_weight considering cpuset partitions
- Extract "imb_numa_nr" calculation into a separate helper
- Allocate per-CPU sched_domain_shared in s_data
- Switch to assigning "sd->shared" from s_data
- Remove sched_domain_shared allocation with sd_data
Energy-aware scheduling updates:
- Filter false overloaded_group case for EAS (Vincent Guittot)
- PM: EM: Switch to rcu_dereference_all() in wakeup path
(Dietmar Eggemann)
Infrastructure updates:
- Replace use of system_unbound_wq with system_dfl_wq (Marco Crivellari)
Proxy scheduling updates by John Stultz:
- Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
- Minimise repeated sched_proxy_exec() checking
- Fix potentially missing balancing with Proxy Exec
- Fix and improve task::blocked_on et al handling
- Add assert_balance_callbacks_empty() helper
- Add logic to zap balancing callbacks if we pick again
- Move attach_one_task() and attach_task() helpers to sched.h
- Handle blocked-waiter migration (and return migration)
- Add K Prateek Nayak to scheduler reviewers for proxy execution
Misc cleanups and fixes by John Stultz, Joseph Salisbury, Peter
Zijlstra, K Prateek Nayak, Michal Koutný, Randy Dunlap, Shrikanth
Hegde, Vincent Guittot, Zhan Xusheng, Xie Yuanbin and Vincent Guittot"
* tag 'sched-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
sched/eevdf: Clear buddies for preempt_short
sched/rt: Cleanup global RT bandwidth functions
sched/rt: Move group schedulability check to sched_rt_global_validate()
sched/rt: Skip group schedulable check with rt_group_sched=0
sched/fair: Avoid overflow in enqueue_entity()
sched: Use u64 for bandwidth ratio calculations
sched/fair: Prevent negative lag increase during delayed dequeue
sched/fair: Use sched_energy_enabled()
sched: Handle blocked-waiter migration (and return migration)
sched: Move attach_one_task and attach_task helpers to sched.h
sched: Add logic to zap balance callbacks if we pick again
sched: Add assert_balance_callbacks_empty helper
sched/locking: Add special p->blocked_on==PROXY_WAKING value for proxy return-migration
sched: Fix modifying donor->blocked on without proper locking
locking: Add task::blocked_lock to serialize blocked_on state
sched: Fix potentially missing balancing with Proxy Exec
sched: Minimise repeated sched_proxy_exec() checking
sched: Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
MAINTAINERS: Add K Prateek Nayak to scheduler reviewers
sched/core: Get this cpu once in ttwu_queue_cond()
...
|
||
|
Linus Torvalds
|
c1fe867b5b |
Updates for the timer/timekeeping core:
- A rework of the hrtimer subsystem to reduce the overhead for frequently
armed timers, especially the hrtick scheduler timer.
- Better timer locality decision
- Simplification of the evaluation of the first expiry time by
keeping track of the neighbor timers in the RB-tree by providing a
RB-tree variant with neighbor links. That avoids walking the
RB-tree on removal to find the next expiry time, but even more
important allows to quickly evaluate whether a timer which is
rearmed changes the position in the RB-tree with the modified
expiry time or not. If not, the dequeue/enqueue sequence which both
can end up in rebalancing can be completely avoided.
- Deferred reprogramming of the underlying clock event device. This
optimizes for the situation where a hrtimer callback sets the need
resched bit. In that case the code attempts to defer the
re-programming of the clock event device up to the point where the
scheduler has picked the next task and has the next hrtick timer
armed. In case that there is no immediate reschedule or soft
interrupts have to be handled before reaching the reschedule point
in the interrupt entry code the clock event is reprogrammed in one
of those code paths to prevent that the timer becomes stale.
- Support for clocksource coupled clockevents
The TSC deadline timer is coupled to the TSC. The next event is
programmed in TSC time. Currently this is done by converting the
CLOCK_MONOTONIC based expiry value into a relative timeout,
converting it into TSC ticks, reading the TSC adding the delta
ticks and writing the deadline MSR.
As the timekeeping core has the conversion factors for the TSC
already, the whole back and forth conversion can be completely
avoided. The timekeeping core calculates the reverse conversion
factors from nanoseconds to TSC ticks and utilizes the base
timestamps of TSC and CLOCK_MONOTONIC which are updated once per
tick. This allows a direct conversion into the TSC deadline value
without reading the time and as a bonus keeps the deadline
conversion in sync with the TSC conversion factors, which are
updated by adjtimex() on systems with NTP/PTP enabled.
- Allow inlining of the clocksource read and clockevent write
functions when they are tiny enough, e.g. on x86 RDTSC and WRMSR.
With all those enhancements in place a hrtick enabled scheduler
provides the same performance as without hrtick. But also other hrtimer
users obviously benefit from these optimizations.
- Robustness improvements and cleanups of historical sins in the hrtimer
and timekeeping code.
- Rewrite of the clocksource watchdog.
The clocksource watchdog code has over time reached the state of an
impenetrable maze of duct tape and staples. The original design, which was
made in the context of systems far smaller than today, is based on the
assumption that the to be monitored clocksource (TSC) can be trivially
compared against a known to be stable clocksource (HPET/ACPI-PM timer).
Over the years this rather naive approach turned out to have major
flaws. Long delays between the watchdog invocations can cause wrap
arounds of the reference clocksource. The access to the reference
clocksource degrades on large multi-sockets systems dure to
interconnect congestion. This has been addressed with various
heuristics which degraded the accuracy of the watchdog to the point
that it fails to detect actual TSC problems on older hardware which
exposes slow inter CPU drifts due to firmware manipulating the TSC to
hide SMI time.
The rewrite addresses this by:
- Restricting the validation against the reference clocksource to the
boot CPU which is usually closest to the legacy block which
contains the reference clocksource (HPET/ACPI-PM).
- Do a round robin validation betwen the boot CPU and the other CPUs
based only on the TSC with an algorithm similar to the TSC
synchronization code during CPU hotplug.
- Being more leniant versus remote timeouts
- The usual tiny fixes, cleanups and enhancements all over the place
-----BEGIN PGP SIGNATURE-----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=2qc8
-----END PGP SIGNATURE-----
Merge tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer core updates from Thomas Gleixner:
- A rework of the hrtimer subsystem to reduce the overhead for
frequently armed timers, especially the hrtick scheduler timer:
- Better timer locality decision
- Simplification of the evaluation of the first expiry time by
keeping track of the neighbor timers in the RB-tree by providing
a RB-tree variant with neighbor links. That avoids walking the
RB-tree on removal to find the next expiry time, but even more
important allows to quickly evaluate whether a timer which is
rearmed changes the position in the RB-tree with the modified
expiry time or not. If not, the dequeue/enqueue sequence which
both can end up in rebalancing can be completely avoided.
- Deferred reprogramming of the underlying clock event device. This
optimizes for the situation where a hrtimer callback sets the
need resched bit. In that case the code attempts to defer the
re-programming of the clock event device up to the point where
the scheduler has picked the next task and has the next hrtick
timer armed. In case that there is no immediate reschedule or
soft interrupts have to be handled before reaching the reschedule
point in the interrupt entry code the clock event is reprogrammed
in one of those code paths to prevent that the timer becomes
stale.
- Support for clocksource coupled clockevents
The TSC deadline timer is coupled to the TSC. The next event is
programmed in TSC time. Currently this is done by converting the
CLOCK_MONOTONIC based expiry value into a relative timeout,
converting it into TSC ticks, reading the TSC adding the delta
ticks and writing the deadline MSR.
As the timekeeping core has the conversion factors for the TSC
already, the whole back and forth conversion can be completely
avoided. The timekeeping core calculates the reverse conversion
factors from nanoseconds to TSC ticks and utilizes the base
timestamps of TSC and CLOCK_MONOTONIC which are updated once per
tick. This allows a direct conversion into the TSC deadline value
without reading the time and as a bonus keeps the deadline
conversion in sync with the TSC conversion factors, which are
updated by adjtimex() on systems with NTP/PTP enabled.
- Allow inlining of the clocksource read and clockevent write
functions when they are tiny enough, e.g. on x86 RDTSC and WRMSR.
With all those enhancements in place a hrtick enabled scheduler
provides the same performance as without hrtick. But also other
hrtimer users obviously benefit from these optimizations.
- Robustness improvements and cleanups of historical sins in the
hrtimer and timekeeping code.
- Rewrite of the clocksource watchdog.
The clocksource watchdog code has over time reached the state of an
impenetrable maze of duct tape and staples. The original design,
which was made in the context of systems far smaller than today, is
based on the assumption that the to be monitored clocksource (TSC)
can be trivially compared against a known to be stable clocksource
(HPET/ACPI-PM timer).
Over the years this rather naive approach turned out to have major
flaws. Long delays between the watchdog invocations can cause wrap
arounds of the reference clocksource. The access to the reference
clocksource degrades on large multi-sockets systems dure to
interconnect congestion. This has been addressed with various
heuristics which degraded the accuracy of the watchdog to the point
that it fails to detect actual TSC problems on older hardware which
exposes slow inter CPU drifts due to firmware manipulating the TSC to
hide SMI time.
The rewrite addresses this by:
- Restricting the validation against the reference clocksource to
the boot CPU which is usually closest to the legacy block which
contains the reference clocksource (HPET/ACPI-PM).
- Do a round robin validation betwen the boot CPU and the other
CPUs based only on the TSC with an algorithm similar to the TSC
synchronization code during CPU hotplug.
- Being more leniant versus remote timeouts
- The usual tiny fixes, cleanups and enhancements all over the place
* tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits)
alarmtimer: Access timerqueue node under lock in suspend
hrtimer: Fix incorrect #endif comment for BITS_PER_LONG check
posix-timers: Fix stale function name in comment
timers: Get this_cpu once while clearing the idle state
clocksource: Rewrite watchdog code completely
clocksource: Don't use non-continuous clocksources as watchdog
x86/tsc: Handle CLOCK_SOURCE_VALID_FOR_HRES correctly
MIPS: Don't select CLOCKSOURCE_WATCHDOG
parisc: Remove unused clocksource flags
hrtimer: Add a helper to retrieve a hrtimer from its timerqueue node
hrtimer: Remove trailing comma after HRTIMER_MAX_CLOCK_BASES
hrtimer: Mark index and clockid of clock base as const
hrtimer: Drop unnecessary pointer indirection in hrtimer_expire_entry event
hrtimer: Drop spurious space in 'enum hrtimer_base_type'
hrtimer: Don't zero-initialize ret in hrtimer_nanosleep()
hrtimer: Remove hrtimer_get_expires_ns()
timekeeping: Mark offsets array as const
timekeeping/auxclock: Consistently use raw timekeeper for tk_setup_internals()
timer_list: Print offset as signed integer
tracing: Use explicit array size instead of sentinel elements in symbol printing
...
|
||
|
Peter Zijlstra
|
14a8570564 |
sched/deadline: Use revised wakeup rule for dl_server
John noted that commit |
||
|
John Stultz
|
e0ca8991b2 |
sched: Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
With proxy-execution, the scheduler selects the donor, but for
blocked donors, we end up running the lock owner.
This caused some complexity, because the class schedulers make
sure to remove the task they pick from their pushable task
lists, which prevents the donor from being migrated, but there
wasn't then anything to prevent rq->curr from being migrated
if rq->curr != rq->donor.
This was sort of hacked around by calling proxy_tag_curr() on
the rq->curr task if we were running something other then the
donor. proxy_tag_curr() did a dequeue/enqueue pair on the
rq->curr task, allowing the class schedulers to remove it from
their pushable list.
The dequeue/enqueue pair was wasteful, and additonally K Prateek
highlighted that we didn't properly undo things when we stopped
proxying, leaving the lock owner off the pushable list.
After some alternative approaches were considered, Peter
suggested just having the RT/DL classes just avoid migrating
when task_on_cpu().
So rework pick_next_pushable_dl_task() and the rt
pick_next_pushable_task() functions so that they skip over the
first pushable task if it is on_cpu.
Then just drop all of the proxy_tag_curr() logic.
Fixes:
|
||
|
Gabriele Monaco
|
c85dbddad7 |
sched/deadline: Move some utility functions to deadline.h
Some utility functions on sched_dl_entity can be useful outside of deadline.c , for instance for modelling, without relying on raw structure fields. Move functions like dl_task_of and dl_is_implicit to deadline.h to make them available outside. Acked-by: Juri Lelli <juri.lelli@redhat.com> Link: https://lore.kernel.org/r/20260330111010.153663-12-gmonaco@redhat.com Signed-off-by: Gabriele Monaco <gmonaco@redhat.com> |
||
|
Gabriele Monaco
|
820725b0eb |
sched: Add deadline tracepoints
Add the following tracepoints:
* sched_dl_throttle(dl_se, cpu, type):
Called when a deadline entity is throttled
* sched_dl_replenish(dl_se, cpu, type):
Called when a deadline entity's runtime is replenished
* sched_dl_update(dl_se, cpu, type):
Called when a deadline entity updates without throttle or replenish
* sched_dl_server_start(dl_se, cpu, type):
Called when a deadline server is started
* sched_dl_server_stop(dl_se, cpu, type):
Called when a deadline server is stopped
Those tracepoints can be useful to validate the deadline scheduler with
RV and are not exported to tracefs.
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20260330111010.153663-11-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
|
||
|
Thomas Gleixner
|
d70c1080a9 |
sched: Avoid ktime_get() indirection
The clock of the hrtick and deadline timers is known to be CLOCK_MONOTONIC. No point in looking it up via hrtimer_cb_get_time(). Just use ktime_get() directly. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260224163429.001511662@kernel.org |
||
|
Tommaso Cucinotta
|
2e7af19269 |
sched/deadline: Add reporting of runtime left & abs deadline to sched_getattr() for DEADLINE tasks
The SCHED_DEADLINE scheduler allows reading the statically configured run-time, deadline, and period parameters through the sched_getattr() system call. However, there is no immediate way to access, from user space, the current parameters used within the scheduler: the instantaneous runtime left in the current cycle, as well as the current absolute deadline. The `flags' sched_getattr() parameter, so far mandated to contain zero, now supports the SCHED_GETATTR_FLAG_DL_DYNAMIC=1 flag, to request retrieval of the leftover runtime and absolute deadline, converted to a CLOCK_MONOTONIC reference, instead of the statically configured parameters. This feature is useful for adaptive SCHED_DEADLINE tasks that need to modify their behavior depending on whether or not there is enough runtime left in the current period, and/or what is the current absolute deadline. Notes: - before returning the instantaneous parameters, the runtime is updated; - the abs deadline is returned shifted from rq_clock() to ktime_get_ns(), in CLOCK_MONOTONIC reference; this causes multiple invocations from the same period to return values that may differ for a few ns (showing some small drift), albeit the deadline doesn't move, in rq_clock() reference; - the abs deadline value returned to user-space, as unsigned 64-bit value, can represent nearly 585 years since boot time; - setting flags=0 provides the old behavior (retrieve static parameters). See also the notes from discussion held at OSPM 2025 on the topic "Making user space aware of current deadline-scheduler parameters". Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@santannapisa.it> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk> Link: https://patch.msgid.link/20250912053937.31636-2-tommaso.cucinotta@santannapisa.it |
||
|
Dengjun Su
|
c0e1832ba6 |
sched: Fix incorrect schedstats for rt and dl thread
For RT and DL thread, only 'set_next_task_(rt/dl)' will call
'update_stats_wait_end_(rt/dl)' to update schedstats information.
However, during the migration process,
'update_stats_wait_start_(rt/dl)' will be called twice, which
will cause the values of wait_max and wait_sum to be incorrect.
The specific output as follows:
$ cat /proc/6046/task/6046/sched | grep wait
wait_start : 0.000000
wait_max : 496717.080029
wait_sum : 7921540.776553
A complete schedstats information update flow of migrate should be
__update_stats_wait_start() [enter queue A, stage 1] ->
__update_stats_wait_end() [leave queue A, stage 2] ->
__update_stats_wait_start() [enter queue B, stage 3] ->
__update_stats_wait_end() [start running on queue B, stage 4]
Stage 1: prev_wait_start is 0, and in the end, wait_start records the
time of entering the queue.
Stage 2: task_on_rq_migrating(p) is true, and wait_start is updated to
the waiting time on queue A.
Stage 3: prev_wait_start is the waiting time on queue A, wait_start is
the time of entering queue B, and wait_start is expected to be greater
than prev_wait_start. Under this condition, wait_start is updated to
(the moment of entering queue B) - (the waiting time on queue A).
Stage 4: the final wait time = (time when starting to run on queue B)
- (time of entering queue B) + (waiting time on queue A) = waiting
time on queue B + waiting time on queue A.
The current problem is that stage 2 does not call __update_stats_wait_end
to update wait_start, which causes the final computed wait time = waiting
time on queue B + the moment of entering queue A, leading to incorrect
wait_max and wait_sum.
Add 'update_stats_wait_end_(rt/dl)' in 'update_stats_dequeue_(rt/dl)' to
update schedstats information when dequeue_task.
Signed-off-by: Dengjun Su <dengjun.su@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260204115959.3183567-1-dengjun.su@mediatek.com
|
||
|
Peter Zijlstra
|
5a40a9bb56 |
sched/debug: Fix dl_server (re)start conditions
There are two problems with sched_server_write_common() that can cause the dl_server to malfunction upon attempting to change the parameters: 1) when, after having disabled the dl_server by setting runtime=0, it is enabled again while tasks are already enqueued. In this case is_active would still be 0 and dl_server_start() would not be called. 2) when dl_server_apply_params() would fail, runtime is not applied and does not reflect the new state. Instead have dl_server_start() check its actual dl_runtime, and have sched_server_write_common() unconditionally (re)start the dl_server. It will automatically stop if there isn't anything to do, so spurious activation is harmless -- while failing to start it is a problem. While there, move the printk out of the locked region and make it symmetric, also printing on enable. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260203103407.GK1282955@noisy.programming.kicks-ass.net |
||
|
Andrea Righi
|
cd959a3562 |
sched_ext: Add a DL server for sched_ext tasks
sched_ext currently suffers starvation due to RT. The same workload when converted to EXT can get zero runtime if RT is 100% running, causing EXT processes to stall. Fix it by adding a DL server for EXT. A kselftest is also included later to confirm that both DL servers are functioning correctly: # ./runner -t rt_stall ===== START ===== TEST: rt_stall DESCRIPTION: Verify that RT tasks cannot stall SCHED_EXT tasks OUTPUT: TAP version 13 1..1 # Runtime of FAIR task (PID 1511) is 0.250000 seconds # Runtime of RT task (PID 1512) is 4.750000 seconds # FAIR task got 5.00% of total runtime ok 1 PASS: FAIR task got more than 4.00% of runtime TAP version 13 1..1 # Runtime of EXT task (PID 1514) is 0.250000 seconds # Runtime of RT task (PID 1515) is 4.750000 seconds # EXT task got 5.00% of total runtime ok 2 PASS: EXT task got more than 4.00% of runtime TAP version 13 1..1 # Runtime of FAIR task (PID 1517) is 0.250000 seconds # Runtime of RT task (PID 1518) is 4.750000 seconds # FAIR task got 5.00% of total runtime ok 3 PASS: FAIR task got more than 4.00% of runtime TAP version 13 1..1 # Runtime of EXT task (PID 1521) is 0.250000 seconds # Runtime of RT task (PID 1522) is 4.750000 seconds # EXT task got 5.00% of total runtime ok 4 PASS: EXT task got more than 4.00% of runtime ok 1 rt_stall # ===== END ===== Co-developed-by: Joel Fernandes <joelagnelf@nvidia.com> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com> Signed-off-by: Andrea Righi <arighi@nvidia.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Tested-by: Christian Loehle <christian.loehle@arm.com> Link: https://patch.msgid.link/20260126100050.3854740-5-arighi@nvidia.com |
||
|
Joel Fernandes
|
3cb3b27693 |
sched/deadline: Clear the defer params
The defer params were not cleared in __dl_clear_params. Clear them.
Without this is some of my test cases are flaking and the DL timer is
not starting correctly AFAICS.
Fixes:
|
||
|
Peter Zijlstra
|
3e4067169c |
Linux 6.19-rc8
-----BEGIN PGP SIGNATURE----- iQFSBAABCgA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAml/zSkeHHRvcnZhbGRz QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiG+bwIAJ0jbbeKDyeJJxPo 8PgScnPJx9vBL3hGpphZrhbV3GOe9bDhKM/0Xk9qMDbpAm9C6qiBMTiDWyvWv5Qi qzDlZfoymMaDLPMxw9WHjJ++i1Z2StNdrz57Vze98C3/iG6gBcKnUEUzvF9nigri HIoxoOKlbSXLPUIzt49xE7YX+CRJhLF/kXmfoauZn5ghpv+uqSpWvRbUQJa3dmc0 S4Ie/nbPtdVHmy1Fz9LJFDOzsdhGyjzHF4kc4shDkjAs8RAr8fJh74mQHO5a3MWA 3WZ7GAAAc4XXNqj76X2dnVlMWpQNJ4p2e+OalsuXGA6VQ7OgbrJGMX8P6dMFn5AF 8hFsXn4= =IdZ1 -----END PGP SIGNATURE----- Merge branch 'v6.19-rc8' Update to avoid conflicts with /urgent patches. Signed-off-by: Peter Zijlstra <peterz@infradead.org> |
||
|
Peter Zijlstra
|
1151354225 |
sched/deadline: Fix 'stuck' dl_server
Andrea reported the dl_server getting stuck for him. He tracked it
down to a state where dl_server_start() saw dl_defer_running==1, but
the dl_server's job is no longer valid at the time of
dl_server_start().
In the state diagram this corresponds to [4] D->A (or dl_server_stop()
due to no more runnable tasks) followed by [1], which in case of a
lapsed deadline must then be A->B.
Now our A has dl_defer_running==1, while B demands
dl_defer_running==0, therefore it must get cleared when the CBS wakeup
rules demand a replenish.
Fixes:
|
||
|
Peter Zijlstra
|
627cc25f84 |
sched/deadline: Use ENQUEUE_MOVE to allow priority change
Pierre reported hitting balance callback warnings for deadline tasks after commit |
||
|
Peter Zijlstra
|
4de9ff7606 |
sched/deadline: Avoid double update_rq_clock()
When setup_new_dl_entity() is called from enqueue_task_dl() ->
enqueue_dl_entity(), the rq-clock should already be updated, and
calling update_rq_clock() again is not right.
Move the update_rq_clock() to the one other caller of
setup_new_dl_entity(): sched_init_dl_server().
Fixes:
|
||
|
Peter Zijlstra
|
375410bb9a |
sched/deadline: Ensure get_prio_dl() is up-to-date
Pratheek tripped a WARN and noted the following issue:
> Inspecting the set of events that led to the warning being triggered
> showed the following:
>
> systemd-1 [008] dN.31 ...: do_set_cpus_allowed: set_cpus_allowed begin!
>
> systemd-1 [008] dN.31 ...: sched_change_begin: Begin!
> systemd-1 [008] dN.31 ...: sched_change_begin: Before dequeue_task()!
> systemd-1 [008] dN.31 ...: update_curr_dl_se: update_curr_dl_se: ENQUEUE_REPLENISH
> systemd-1 [008] dN.31 ...: enqueue_dl_entity: enqueue_dl_entity: ENQUEUE_REPLENISH
> systemd-1 [008] dN.31 ...: replenish_dl_entity: Replenish before: 14815760217
> systemd-1 [008] dN.31 ...: replenish_dl_entity: Replenish after: 14816960047
> systemd-1 [008] dN.31 ...: sched_change_begin: Before put_prev_task()!
>
> systemd-1 [008] dN.31 ...: sched_change_end: Before enqueue_task()!
> systemd-1 [008] dN.31 ...: sched_change_end: Before put_prev_task()!
> systemd-1 [008] dN.31 ...: prio_changed_dl: Queuing pull task on prio change: 14815760217 -> 14816960047
> systemd-1 [008] dN.31 ...: prio_changed_dl: Queuing balance callback!
> systemd-1 [008] dN.31 ...: sched_change_end: End!
>
> systemd-1 [008] dN.31 ...: do_set_cpus_allowed: set_cpus_allowed end!
> systemd-1 [008] dN.21 ...: __schedule: Woops! Balance callback found!
>
> 1. sched_change_begin() from guard(sched_change) in
> do_set_cpus_allowed() stashes the priority, which for the deadline
> task, is "p->dl.deadline".
> 2. The dequeue of the deadline task replenishes the deadline.
> 3. The task is enqueued back after guard's scope ends and since there is
> no *_CLASS flags set, sched_change_end() calls
> dl_sched_class->prio_changed() which compares the deadline.
> 4. Since deadline was moved on dequeue, prio_changed_dl() sees the value
> differ from the stashed value and queues a balance pull callback.
> 5. do_set_cpus_allowed() finishes and drops the rq_lock without doing a
> do_balance_callbacks().
> 6. Grabbing the rq_lock() at subsequent __schedule() triggers the
> warning since the balance pull callback was never executed before
> dropping the lock.
Meaning get_prio_dl() ought to update current and return an up-to-date
value.
Fixes:
|
||
|
Gabriele Monaco
|
ca1e8eede4 |
sched/deadline: Fix server stopping with runnable tasks
The deadline server can currently stop due to idle although fair tasks
are runnable. This happens essentially when:
* the server is set to idle, a task wakes up, the server stops
* a task wakes up, the server sets itself to idle and stops right away
Address both cases by clearing the server idle flag whenever a fair task
wakes up and accounting also for pending tasks in the definition of idle.
Fixes:
|
||
|
Pingfan Liu
|
64e6fa7661 |
sched/deadline: Fix potential race in dl_add_task_root_domain()
The access rule for local_cpu_mask_dl requires it to be called on the
local CPU with preemption disabled. However, dl_add_task_root_domain()
currently violates this rule.
Without preemption disabled, the following race can occur:
1. ThreadA calls dl_add_task_root_domain() on CPU 0
2. Gets pointer to CPU 0's local_cpu_mask_dl
3. ThreadA is preempted and migrated to CPU 1
4. ThreadA continues using CPU 0's local_cpu_mask_dl
5. Meanwhile, the scheduler on CPU 0 calls find_later_rq() which also
uses local_cpu_mask_dl (with preemption properly disabled)
6. Both contexts now corrupt the same per-CPU buffer concurrently
Fix this by moving the local_cpu_mask_dl access to the preemption
disabled section.
Closes: https://lore.kernel.org/lkml/aSBjm3mN_uIy64nz@jlelli-thinkpadt14gen4.remote.csb
Fixes:
|
||
|
Pingfan Liu
|
479972efc2 |
sched/deadline: Remove unnecessary comment in dl_add_task_root_domain()
The comments above dl_get_task_effective_cpus() and dl_add_task_root_domain() already explain how to fetch a valid root domain and protect against races. There's no need to repeat this inside dl_add_task_root_domain(). Remove the redundant comment to keep the code clean. No functional change. Signed-off-by: Pingfan Liu <piliu@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Acked-by: Waiman Long <longman@redhat.com> Link: https://patch.msgid.link/20251125032630.8746-2-piliu@redhat.com |
||
|
Peter Zijlstra
|
704069649b |
sched/core: Rework sched_class::wakeup_preempt() and rq_modified_*()
Change sched_class::wakeup_preempt() to also get called for cross-class wakeups, specifically those where the woken task is of a higher class than the previous highest class. In order to do this, track the current highest class of the runqueue in rq::next_class and have wakeup_preempt() track this upwards for each new wakeup. Additionally have schedule() re-set the value on pick. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://patch.msgid.link/20251127154725.901391274@infradead.org |
||
|
Linus Torvalds
|
8449d3252c |
cgroup: Changes for v6.19
- Defer task cgroup unlink until after the dying task's final context switch so that controllers see the cgroup properly populated until the task is truly gone. - cpuset cleanups and simplifications. Enforce that domain isolated CPUs stay in root or isolated partitions and fail if isolated+nohz_full would leave no housekeeping CPU. Fix sched/deadline root domain handling during CPU hot-unplug and race for tasks in attaching cpusets. - Misc fixes including memory reclaim protection documentation and selftest KTAP conformance. -----BEGIN PGP SIGNATURE----- iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCaS3pEQ4cdGpAa2VybmVs Lm9yZwAKCRCxYfJx3gVYGYbrAP9H0kVyWH5tK9VhjSZyqidic8NuvtmNOyhIRrg0 8S8K0wD/YG9xlh2JUyRmS4B23ggc59+9y5xM2/sctrho51Pvsgg= =0MB+ -----END PGP SIGNATURE----- Merge tag 'cgroup-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: - Defer task cgroup unlink until after the dying task's final context switch so that controllers see the cgroup properly populated until the task is truly gone - cpuset cleanups and simplifications. Enforce that domain isolated CPUs stay in root or isolated partitions and fail if isolated+nohz_full would leave no housekeeping CPU. Fix sched/deadline root domain handling during CPU hot-unplug and race for tasks in attaching cpusets - Misc fixes including memory reclaim protection documentation and selftest KTAP conformance * tag 'cgroup-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits) cpuset: Treat cpusets in attaching as populated sched/deadline: Walk up cpuset hierarchy to decide root domain when hot-unplug cgroup/cpuset: Introduce cpuset_cpus_allowed_locked() docs: cgroup: No special handling of unpopulated memcgs docs: cgroup: Note about sibling relative reclaim protection docs: cgroup: Explain reclaim protection target selftests/cgroup: conform test to KTAP format output cpuset: remove need_rebuild_sched_domains cpuset: remove global remote_children list cpuset: simplify node setting on error cgroup: include missing header for struct irq_work cgroup: Fix sleeping from invalid context warning on PREEMPT_RT cgroup/cpuset: Globally track isolated_cpus update cgroup/cpuset: Ensure domain isolated CPUs stay in root or isolated partition cgroup/cpuset: Move up prstate_housekeeping_conflict() helper cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping cgroup/cpuset: Rename update_unbound_workqueue_cpumask() to update_isolation_cpumasks() cgroup: Defer task cgroup unlink until after the task is done switching out cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free() cgroup: Rename cgroup lifecycle hooks to cgroup_task_*() ... |
||
|
Pingfan Liu
|
318e18ed22 |
sched/deadline: Walk up cpuset hierarchy to decide root domain when hot-unplug
*** Bug description *** When testing kexec-reboot on a 144 cpus machine with isolcpus=managed_irq,domain,1-71,73-143 in kernel command line, I encounter the following bug: [ 97.114759] psci: CPU142 killed (polled 0 ms) [ 97.333236] Failed to offline CPU143 - error=-16 [ 97.333246] ------------[ cut here ]------------ [ 97.342682] kernel BUG at kernel/cpu.c:1569! [ 97.347049] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP [...] In essence, the issue originates from the CPU hot-removal process, not limited to kexec. It can be reproduced by writing a SCHED_DEADLINE program that waits indefinitely on a semaphore, spawning multiple instances to ensure some run on CPU 72, and then offlining CPUs 1–143 one by one. When attempting this, CPU 143 failed to go offline. bash -c 'taskset -cp 0 $$ && for i in {1..143}; do echo 0 > /sys/devices/system/cpu/cpu$i/online 2>/dev/null; done' Tracking down this issue, I found that dl_bw_deactivate() returned -EBUSY, which caused sched_cpu_deactivate() to fail on the last CPU. But that is not the fact, and contributed by the following factors: When a CPU is inactive, cpu_rq()->rd is set to def_root_domain. For an blocked-state deadline task (in this case, "cppc_fie"), it was not migrated to CPU0, and its task_rq() information is stale. So its rq->rd points to def_root_domain instead of the one shared with CPU0. As a result, its bandwidth is wrongly accounted into a wrong root domain during domain rebuild. *** Issue *** The key point is that root_domain is only tracked through active rq->rd. To avoid using a global data structure to track all root_domains in the system, there should be a method to locate an active CPU within the corresponding root_domain. *** Solution *** To locate the active cpu, the following rules for deadline sub-system is useful -1.any cpu belongs to a unique root domain at a given time -2.DL bandwidth checker ensures that the root domain has active cpus. Now, let's examine the blocked-state task P. If P is attached to a cpuset that is a partition root, it is straightforward to find an active CPU. If P is attached to a cpuset that has changed from 'root' to 'member', the active CPUs are grouped into the parent root domain. Naturally, the CPUs' capacity and reserved DL bandwidth are taken into account in the ancestor root domain. (In practice, it may be unsafe to attach P to an arbitrary root domain, since that domain may lack sufficient DL bandwidth for P.) Again, it is straightforward to find an active CPU in the ancestor root domain. This patch groups CPUs into isolated and housekeeping sets. For the housekeeping group, it walks up the cpuset hierarchy to find active CPUs in P's root domain and retrieves the valid rd from cpu_rq(cpu)->rd. Signed-off-by: Pingfan Liu <piliu@redhat.com> Cc: Waiman Long <longman@redhat.com> Cc: Chen Ridong <chenridong@huaweicloud.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Pierre Gondois <pierre.gondois@arm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Segall <bsegall@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Valentin Schneider <vschneid@redhat.com> To: linux-kernel@vger.kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> |
||
|
Shrikanth Hegde
|
65177ea9f6 |
sched/deadline: Minor cleanup in select_task_rq_dl()
In select_task_rq_dl, there is only one goto statement, there is no need for it. No functional changes. Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Link: https://patch.msgid.link/20251014100342.978936-2-sshegde@linux.ibm.com |
||
|
Shrikanth Hegde
|
b4bfacd392 |
sched/deadline: Use cpumask_weight_and() in dl_bw_cpus
cpumask_subset(a,b) -> cpumask_weight(a) should be same as cpumask_weight_and(a,b) for_each_cpu_and(a,b) to count cpus could be replaced by cpumask_weight_and(a,b) No Functional Change. It could save a few cycles since cpumask_weight_and would be more efficient. Plus one less stack variable. Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Link: https://patch.msgid.link/20251014100342.978936-3-sshegde@linux.ibm.com |
||
|
Peter Zijlstra
|
2614069c59 |
sched/deadline: Document dl_server
Place the notes that resulted from going through the dl_server code in a comment. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
||
|
Peter Zijlstra
|
f5a538c07d |
sched/deadline: Fix dl_server stop condition
Gabriel reported that the dl_server doesn't stop as expected.
The problem was found to be the fact that idle time and fair runtime are
treated equally. Both will count towards dl_server runtime and push the
activation forwards when it is in the zero-laxity wait state.
Notably:
dl_server_update_idle()
update_curr_dl_se()
if (dl_defer && dl_throttled && dl_runtime_exceeded())
hrtimer_try_to_cancel(); // stop timer
replenish_dl_new_period()
deadline = now + dl_deadline; // fwd period
runtime = dl_runtime;
start_dl_timer(); // restart timer
And while we do want idle time accounted towards the *current* activation of
the dl_server -- after all, a fair task could've ran if we had any -- we don't
necessarily want idle time to cause or push forward an activation.
Introduce dl_defer_idle to make this distinction. It will be set once idle time
pushed the activation forward, once set idle time will only be allowed to
consume any runtime but not push the activation. This will then cause
dl_server_timer() to fire, which will stop the dl_server.
Any non-idle time accounting during this phase will clear dl_defer_idle, so
only a full period of idle will cause the dl_server to stop.
Reported-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251101000057.GA2184199@noisy.programming.kicks-ass.net
|
||
|
Peter Zijlstra
|
e636ffb9e3 |
sched/deadline: Fix dl_server time accounting
The dl_server time accounting code is a little odd. The normal scheduler pattern is to update curr before doing something, such that the old state is fully accounted before changing state. Notably, the dl_server_timer() needs to propagate the current time accounting since the current task could be ran by dl_server and thus this can affect dl_se->runtime. Similarly for dl_server_start(). And since the (deferred) dl_server wants idle time accounted, rework sched_idle_class time accounting to be more like all the others. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20251020141130.GJ3245006@noisy.programming.kicks-ass.net |
||
|
Fernand Sieber
|
127b90315c |
sched/proxy: Yield the donor task
When executing a task in proxy context, handle yields as if they were requested by the donor task. This matches the traditional PI semantics of yield() as well. This avoids scenario like proxy task yielding, pick next task selecting the same previous blocked donor, running the proxy task again, etc. Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202510211205.1e0f5223-lkp@intel.com Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Fernand Sieber <sieberf@amazon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20251106104022.195157-1-sieberf@amazon.com |
||
|
Peter Zijlstra
|
977b9a0054 |
Merge branch 'linus/master' into sched/core, to resolve conflict
Conflicts: kernel/sched/ext.c Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Joel Fernandes
|
50653216e4 |
sched: Add support to pick functions to take rf
Some pick functions like the internal pick_next_task_fair() already take
rf but some others dont. We need this for scx's server pick function.
Prepare for this by having pick functions accept it.
[peterz: - added RETRY_TASK handling
- removed pick_next_task_fair indirection]
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
|
||
|
Peter Zijlstra
|
1e900f415c |
sched: Detect per-class runqueue changes
Have enqueue/dequeue set a per-class bit in rq->queue_mask. This then enables easy tracking of which runqueues are modified over a lock-break. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Tejun Heo <tj@kernel.org> |
||
|
Peter Zijlstra
|
6455ad5346 |
sched: Move sched_class::prio_changed() into the change pattern
Move sched_class::prio_changed() into the change pattern. And while there, extend it with sched_class::get_prio() in order to fix the deadline sitation. Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> |
||
|
Peter Zijlstra
|
5e42d4c123 |
sched/deadline: Prepare for switched_from() change
Prepare for the sched_class::switch*() methods getting folded into the change pattern. As a result of that, the location of switched_from will change slightly. SCHED_DEADLINE is affected by this change in location: OLD NEW | | switching_from() dequeue_task(); | dequeue_task() put_prev_task(); | put_prev_task() | switched_from() | ... change task ... | ... change task ... | switching_to(); | switching_to() enqueue_task(); | enqueue_task() set_next_task(); | set_next_task() prev_class->switched_from() | switched_to() | switched_to() | Notably, where switched_from() was called *after* the change to the task, it will get called before it. Specifically, switched_from_dl() uses dl_task(p) which uses p->prio; which is changed when switching class (it might be the reason to switch class in case of PI). When switched_from_dl() gets called, the task will have left the deadline class and dl_task() must be false, while when doing dequeue_dl_entity() the task must be a dl_task(), otherwise we'd have called a different dequeue method. Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
||
|
Doug Berger
|
382748c05e |
sched/deadline: only set free_cpus for online runqueues
Commit |
||
|
Peter Zijlstra (Intel)
|
ee6e44dfe6 |
sched/deadline: Stop dl_server before CPU goes offline
IBM CI tool reported kernel warning[1] when running a CPU removal operation through drmgr[2]. i.e "drmgr -c cpu -r -q 1" WARNING: CPU: 0 PID: 0 at kernel/sched/cpudeadline.c:219 cpudl_set+0x58/0x170 NIP [c0000000002b6ed8] cpudl_set+0x58/0x170 LR [c0000000002b7cb8] dl_server_timer+0x168/0x2a0 Call Trace: [c000000002c2f8c0] init_stack+0x78c0/0x8000 (unreliable) [c0000000002b7cb8] dl_server_timer+0x168/0x2a0 [c00000000034df84] __hrtimer_run_queues+0x1a4/0x390 [c00000000034f624] hrtimer_interrupt+0x124/0x300 [c00000000002a230] timer_interrupt+0x140/0x320 Git bisects to: commit |
||
|
Linus Torvalds
|
6c7340a7a8 |
Scheduler updates for v6.18:
Core scheduler changes:
- Make migrate_{en,dis}able() inline, to improve performance
(Menglong Dong)
- Move STDL_INIT() functions out-of-line (Peter Zijlstra)
- Unify the SCHED_{SMT,CLUSTER,MC} Kconfig (Peter Zijlstra)
Fair scheduling:
- Defer throttling when tasks exit to user-space, to reduce the
chance & impact of throttle-preemption with held locks and
other resources. (Aaron Lu, Valentin Schneider)
- Get rid of sched_domains_curr_level hack for tl->cpumask(),
as the warning was getting triggered on certain topologies.
(Peter Zijlstra)
Misc cleanups & fixes:
- Header cleanups (Menglong Dong)
- Fix race in push_dl_task() (Harshit Agarwal)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=8ZTZ
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core scheduler changes:
- Make migrate_{en,dis}able() inline, to improve performance
(Menglong Dong)
- Move STDL_INIT() functions out-of-line (Peter Zijlstra)
- Unify the SCHED_{SMT,CLUSTER,MC} Kconfig (Peter Zijlstra)
Fair scheduling:
- Defer throttling to when tasks exit to user-space, to reduce the
chance & impact of throttle-preemption with held locks and other
resources (Aaron Lu, Valentin Schneider)
- Get rid of sched_domains_curr_level hack for tl->cpumask(), as the
warning was getting triggered on certain topologies (Peter
Zijlstra)
Misc cleanups & fixes:
- Header cleanups (Menglong Dong)
- Fix race in push_dl_task() (Harshit Agarwal)"
* tag 'sched-core-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Fix some typos in include/linux/preempt.h
sched: Make migrate_{en,dis}able() inline
rcu: Replace preempt.h with sched.h in include/linux/rcupdate.h
arch: Add the macro COMPILE_OFFSETS to all the asm-offsets.c
sched/fair: Do not balance task to a throttled cfs_rq
sched/fair: Do not special case tasks in throttled hierarchy
sched/fair: update_cfs_group() for throttled cfs_rqs
sched/fair: Propagate load for throttled cfs_rq
sched/fair: Get rid of throttled_lb_pair()
sched/fair: Task based throttle time accounting
sched/fair: Switch to task based throttle model
sched/fair: Implement throttle task work and related helpers
sched/fair: Add related data structure for task based throttle
sched: Unify the SCHED_{SMT,CLUSTER,MC} Kconfig
sched: Move STDL_INIT() functions out-of-line
sched/fair: Get rid of sched_domains_curr_level hack for tl->cpumask()
sched/deadline: Fix race in push_dl_task()
|
||
|
Peter Zijlstra
|
a3a70caf79 |
sched/deadline: Fix dl_server behaviour
John reported undesirable behaviour with the dl_server since commit: |
||
|
Peter Zijlstra
|
4ae8d9aa9f |
sched/deadline: Fix dl_server getting stuck
John found it was easy to hit lockup warnings when running locktorture on a 2 CPU VM, which he bisected down to: commit |
||
|
Harshit Agarwal
|
8fd5485fb4 |
sched/deadline: Fix race in push_dl_task()
When a CPU chooses to call push_dl_task and picks a task to push to another CPU's runqueue then it will call find_lock_later_rq method which would take a double lock on both CPUs' runqueues. If one of the locks aren't readily available, it may lead to dropping the current runqueue lock and reacquiring both the locks at once. During this window it is possible that the task is already migrated and is running on some other CPU. These cases are already handled. However, if the task is migrated and has already been executed and another CPU is now trying to wake it up (ttwu) such that it is queued again on the runqeue (on_rq is 1) and also if the task was run by the same CPU, then the current checks will pass even though the task was migrated out and is no longer in the pushable tasks list. Please go through the original rt change for more details on the issue. To fix this, after the lock is obtained inside the find_lock_later_rq, it ensures that the task is still at the head of pushable tasks list. Also removed some checks that are no longer needed with the addition of this new check. However, the new check of pushable tasks list only applies when find_lock_later_rq is called by push_dl_task. For the other caller i.e. dl_task_offline_migration, existing checks are used. Signed-off-by: Harshit Agarwal <harshit@nutanix.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250408045021.3283624-1-harshit@nutanix.com |
||
|
Yicong Yang
|
52d15521eb |
sched/deadline: Don't count nr_running for dl_server proxy tasks
On CPU offline the kernel stalled with below call trace:
INFO: task kworker/0:1:11 blocked for more than 120 seconds.
cpuhp hold the cpu hotplug lock endless and stalled vmstat_shepherd.
This is because we count nr_running twice on cpuhp enqueuing and failed
the wait condition of cpuhp:
enqueue_task_fair() // pick cpuhp from idle, rq->nr_running = 0
dl_server_start()
[...]
add_nr_running() // rq->nr_running = 1
add_nr_running() // rq->nr_running = 2
[switch to cpuhp, waiting on balance_hotplug_wait()]
rcuwait_wait_event(rq->nr_running == 1 && ...) // failed, rq->nr_running=2
schedule() // wait again
It doesn't make sense to count the dl_server towards runnable tasks,
since it runs other tasks.
Fixes:
|