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sched: Account cgroup CPU time to the execution context

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Proxy execution separates the scheduling context from the execution
context. Commit aa4f74dfd4 ("sched: Fix runtime accounting w/ split
exec & sched contexts") made per-task and thread-group runtime
accounting follow the task that actually executes, while cgroup CPU
usage is charged to the donor.

When the donor and execution task belong to different cgroups, this
makes a task's execution time count against a different cgroup from the
one the task belongs to.

Cgroup CPU usage should follow the execution context, matching the
per-task, thread-group, and cgroup user/system accounting. Keep
scheduling state associated with the donor, but charge cgroup CPU
usage to rq->curr.

A reproducer with the donor and execution task in separate cgroups
showed the execution task accumulating runtime while cgroup CPU usage
was charged to the donor's cgroup. With this change, the execution
task's cgroup accumulates the CPU usage instead. The same behavior was
verified with an RT donor and with legacy cpuacct accounting.

Fixes: aa4f74dfd4 ("sched: Fix runtime accounting w/ split exec & sched contexts")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260904034707.268416-1-sh_def@163.com
This commit is contained in:
Hui Su 2026-09-04 11:47:07 +08:00 committed by Peter Zijlstra
parent 51b0e68cfa
commit c23810313b
1 changed files with 1 additions and 3 deletions
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4
kernel/sched/fair.c
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@ -1414,7 +1414,6 @@ static s64 update_se(struct rq *rq, struct sched_entity *se)
se->exec_start = now;
if (entity_is_task(se)) {
struct task_struct *donor = task_of(se);
struct task_struct *running = rq->curr;
/*
* If se is a task, we account the time against the running
@ -1427,8 +1426,7 @@ static s64 update_se(struct rq *rq, struct sched_entity *se)
account_group_exec_runtime(running, delta_exec);
account_mm_sched(rq, running, delta_exec);
/* cgroup time is always accounted against the donor */
cgroup_account_cputime(donor, delta_exec);
cgroup_account_cputime(running, delta_exec);
} else {
/* If not task, account the time against donor se */
se->sum_exec_runtime += delta_exec;