linux/kernel/sched
Shrikanth Hegde 5bc6ab2d42 sched: Simplify ifdeffery around cpu_smt_mask
Now, that cpu_smt_mask is defined as cpumask_of(cpu) for
CONFIG_SCHED_SMT=n, it is possible to get rid of the ifdeffery.

Effectively,
 - This makes sched_smt_present is defined always

 - cpumask_weight(cpumask_of(cpu)) == 1. So sched_smt_present_inc/dec
   will never enable the sched_smt_present. Which is expected.

 - Paths that were compile-time eliminated become runtime guarded
   using static keys.

 - Defines set_idle_cores, test_idle_cores, etc which could likely benefit
   the CONFIG_SCHED_SMT=n systems to use the same optimizations within the
   LLC at wakeups.

 - This will expose sched_smt_present symbol for CONFIG_SCHED_SMT=n.
   Likely not a concern.

 - There is a bloat of code CONFIG_SCHED_SMT=n. (NR_CPUS=2048)
   add/remove: 24/18 grow/shrink: 26/28 up/down: 6396/-3188 (3208)
   Total: Before=30629880, After=30633088, chg +0.01%

 - No code bloat for CONFIG_SCHED_SMT=y, which is expected.

 - Add comments around stop_core_cpuslocked on why ifdefs are not
   removed.

 - This leaves the remaining uses of CONFIG_SCHED_SMT mainly for
   topology building bits which has a policy based decision.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://patch.msgid.link/20260515172456.542799-3-sshegde@linux.ibm.com
2026-05-19 12:17:37 +02:00
..
autogroup.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
autogroup.h
build_policy.c sched_ext: Move internal type and accessor definitions to ext_internal.h 2025-09-03 11:33:28 -10:00
build_utility.c
clock.c sched/clock: Avoid false sharing for sched_clock_irqtime 2026-02-03 12:04:19 +01:00
completion.c
core_sched.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
core.c sched: Simplify ifdeffery around cpu_smt_mask 2026-05-19 12:17:37 +02:00
cpuacct.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cpudeadline.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cpudeadline.h sched/deadline: only set free_cpus for online runqueues 2025-10-16 11:13:49 +02:00
cpufreq_schedutil.c cpufreq: Pass the policy to cpufreq_driver->adjust_perf() 2026-04-02 11:30:24 -05:00
cpufreq.c
cpupri.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cpupri.h
cputime.c sched/cputime: Drop now-stale mul_u64_u64_div_u64() over-approximation guard 2026-05-19 12:17:35 +02:00
deadline.c sched/deadline: Fix replenishment logic for non-deferred servers 2026-05-19 12:17:35 +02:00
debug.c Merge branch 'sched/urgent' into sched/core, to resolve conflicts 2026-04-02 15:04:09 +02:00
ext_idle.c sched: Simplify ifdeffery around cpu_smt_mask 2026-05-19 12:17:37 +02:00
ext_idle.h sched_ext: Deny SCX kfuncs to non-SCX struct_ops programs 2026-04-20 07:57:29 -10:00
ext_internal.h sched_ext: Make bypass LB cpumasks per-scheduler 2026-04-24 14:31:36 -10:00
ext.c sched_ext: Fixes for v7.1-rc1 2026-04-28 16:26:11 -07:00
ext.h sched_ext: Add @kargs to scx_fork() 2026-03-06 07:58:02 -10:00
fair.c sched: Simplify ifdeffery around cpu_smt_mask 2026-05-19 12:17:37 +02:00
features.h Scheduler changes for v7.1: 2026-04-14 13:33:36 -07:00
idle.c sched: idle: Consolidate the handling of two special cases 2026-03-16 20:29:47 +01:00
isolation.c cgroup/cpuset: Call housekeeping_update() without holding cpus_read_lock 2026-02-23 10:46:49 -10:00
loadavg.c
Makefile sched: Enable context analysis for core.c and fair.c 2026-01-05 16:43:36 +01:00
membarrier.c rseq: Simplify the event notification 2025-11-04 08:30:09 +01:00
pelt.c treewide: Update email address 2026-01-11 06:09:11 -10:00
pelt.h sched/fair: Switch to task based throttle model 2025-09-03 10:03:14 +02:00
psi.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
rq-offsets.c sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
rt.c sched/rt: Update default bandwidth for real-time tasks to ONE 2026-05-19 12:17:35 +02:00
sched-pelt.h
sched.h sched: Simplify ifdeffery around cpu_smt_mask 2026-05-19 12:17:37 +02:00
smp.h
stats.c
stats.h delayacct: add timestamp of delay max 2026-01-31 16:16:06 -08:00
stop_task.c sched/core: Rework sched_class::wakeup_preempt() and rq_modified_*() 2025-12-17 10:53:25 +01:00
swait.c
syscalls.c Linux 7.0-rc4 2026-03-17 07:14:42 +01:00
topology.c sched: Simplify ifdeffery around cpu_smt_mask 2026-05-19 12:17:37 +02:00
wait_bit.c
wait.c