diff options
| author | Dawei Li <daweilics@gmail.com> | 2024-03-15 02:59:16 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2024-05-17 09:49:44 +0200 |
| commit | 72bffbf57c5247ac6146d1103ef42e9f8d094bc8 (patch) | |
| tree | 2eaf427114098793768a7a252c9a49690e76799f /kernel/sched | |
| parent | docs: cgroup-v1: Clarify that domain levels are system-specific (diff) | |
| download | linux-72bffbf57c5247ac6146d1103ef42e9f8d094bc8.tar.xz linux-72bffbf57c5247ac6146d1103ef42e9f8d094bc8.zip | |
sched/fair: Fix initial util_avg calculation
Change se->load.weight to se_weight(se) in the calculation for the
initial util_avg to avoid unnecessarily inflating the util_avg by 1024
times.
The reason is that se->load.weight has the unit/scale as the scaled-up
load, while cfs_rg->avg.load_avg has the unit/scale as the true task
weight (as mapped directly from the task's nice/priority value). With
CONFIG_32BIT, the scaled-up load is equal to the true task weight. With
CONFIG_64BIT, the scaled-up load is 1024 times the true task weight.
Thus, the current code may inflate the util_avg by 1024 times. The
follow-up capping will not allow the util_avg value to go wild. But the
calculation should have the correct logic.
Signed-off-by: Dawei Li <daweilics@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Vishal Chourasia <vishalc@linux.ibm.com>
Link: https://lore.kernel.org/r/20240315015916.21545-1-daweilics@gmail.com
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 146ecf9cc3af..900978741a81 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1031,7 +1031,8 @@ void init_entity_runnable_average(struct sched_entity *se) * With new tasks being created, their initial util_avgs are extrapolated * based on the cfs_rq's current util_avg: * - * util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight + * util_avg = cfs_rq->avg.util_avg / (cfs_rq->avg.load_avg + 1) + * * se_weight(se) * * However, in many cases, the above util_avg does not give a desired * value. Moreover, the sum of the util_avgs may be divergent, such @@ -1078,7 +1079,7 @@ void post_init_entity_util_avg(struct task_struct *p) if (cap > 0) { if (cfs_rq->avg.util_avg != 0) { - sa->util_avg = cfs_rq->avg.util_avg * se->load.weight; + sa->util_avg = cfs_rq->avg.util_avg * se_weight(se); sa->util_avg /= (cfs_rq->avg.load_avg + 1); if (sa->util_avg > cap) |