diff options
| author | Mel Gorman <mgorman@techsingularity.net> | 2021-01-25 08:59:06 +0000 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-01-27 17:26:43 +0100 |
| commit | e6e0dc2d5497f7f3ed970052917e2923c6f453f4 (patch) | |
| tree | ed7ddaf907a849aa8e16e5c932b6d97f79cbf6af /kernel/sched/fair.c | |
| parent | 1875dc5b8ff4690547c446ef222083e28e2d9463 (diff) | |
sched/fair: Remove SIS_AVG_CPU
SIS_AVG_CPU was introduced as a means of avoiding a search when the
average search cost indicated that the search would likely fail. It was
a blunt instrument and disabled by commit 4c77b18cf8b7 ("sched/fair: Make
select_idle_cpu() more aggressive") and later replaced with a proportional
search depth by commit 1ad3aaf3fcd2 ("sched/core: Implement new approach
to scale select_idle_cpu()").
While there are corner cases where SIS_AVG_CPU is better, it has now been
disabled for almost three years. As the intent of SIS_PROP is to reduce
the time complexity of select_idle_cpu(), lets drop SIS_AVG_CPU and focus
on SIS_PROP as a throttling mechanism.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210125085909.4600-2-mgorman@techsingularity.net
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9379a481dd8c..124cb6ec6b7b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6158,7 +6158,6 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t { struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); struct sched_domain *this_sd; - u64 avg_cost, avg_idle; u64 time; int this = smp_processor_id(); int cpu, nr = INT_MAX; @@ -6167,18 +6166,17 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t if (!this_sd) return -1; - /* - * Due to large variance we need a large fuzz factor; hackbench in - * particularly is sensitive here. - */ - avg_idle = this_rq()->avg_idle / 512; - avg_cost = this_sd->avg_scan_cost + 1; + if (sched_feat(SIS_PROP)) { + u64 avg_cost, avg_idle, span_avg; - if (sched_feat(SIS_AVG_CPU) && avg_idle < avg_cost) - return -1; + /* + * Due to large variance we need a large fuzz factor; + * hackbench in particularly is sensitive here. + */ + avg_idle = this_rq()->avg_idle / 512; + avg_cost = this_sd->avg_scan_cost + 1; - if (sched_feat(SIS_PROP)) { - u64 span_avg = sd->span_weight * avg_idle; + span_avg = sd->span_weight * avg_idle; if (span_avg > 4*avg_cost) nr = div_u64(span_avg, avg_cost); else |