diff options
| author | Josh Don <joshdon@google.com> | 2021-10-18 13:34:28 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-11-17 14:49:00 +0100 |
| commit | 4feee7d12603deca8775f9f9ae5e121093837444 (patch) | |
| tree | 5b4d68bde6fbd540ec521237d75892b617241eac /kernel/sched/fair.c | |
| parent | 2fb75e1b642f49253d8848c9e47e8942f5366221 (diff) | |
sched/core: Forced idle accounting
Adds accounting for "forced idle" time, which is time where a cookie'd
task forces its SMT sibling to idle, despite the presence of runnable
tasks.
Forced idle time is one means to measure the cost of enabling core
scheduling (ie. the capacity lost due to the need to force idle).
Forced idle time is attributed to the thread responsible for causing
the forced idle.
A few details:
- Forced idle time is displayed via /proc/PID/sched. It also requires
that schedstats is enabled.
- Forced idle is only accounted when a sibling hyperthread is held
idle despite the presence of runnable tasks. No time is charged if
a sibling is idle but has no runnable tasks.
- Tasks with 0 cookie are never charged forced idle.
- For SMT > 2, we scale the amount of forced idle charged based on the
number of forced idle siblings. Additionally, we split the time up and
evenly charge it to all running tasks, as each is equally responsible
for the forced idle.
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211018203428.2025792-1-joshdon@google.com
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6e476f6d9435..884f29d07963 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -11068,7 +11068,7 @@ static inline void task_tick_core(struct rq *rq, struct task_struct *curr) * MIN_NR_TASKS_DURING_FORCEIDLE - 1 tasks and use that to check * if we need to give up the CPU. */ - if (rq->core->core_forceidle && rq->cfs.nr_running == 1 && + if (rq->core->core_forceidle_count && rq->cfs.nr_running == 1 && __entity_slice_used(&curr->se, MIN_NR_TASKS_DURING_FORCEIDLE)) resched_curr(rq); } |