Messages in this thread | | | Subject | Re: [RFC PATCH 9/9] sched: rotate the cpu search window for better spread | From | Parth Shah <> | Date | Thu, 5 Sep 2019 12:07:47 +0530 |
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On 8/30/19 11:19 PM, subhra mazumdar wrote: > Rotate the cpu search window for better spread of threads. This will ensure > an idle cpu will quickly be found if one exists. > > Signed-off-by: subhra mazumdar <subhra.mazumdar@oracle.com> > --- > kernel/sched/fair.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 94dd4a32..7419b47 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6188,7 +6188,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t > u64 avg_cost, avg_idle; > u64 time, cost; > s64 delta; > - int cpu, floor, nr = INT_MAX; > + int cpu, floor, target_tmp, nr = INT_MAX; > > this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); > if (!this_sd) > @@ -6213,9 +6213,15 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t > nr = floor; > } > > + if (per_cpu(next_cpu, target) != -1) > + target_tmp = per_cpu(next_cpu, target); > + else > + target_tmp = target; > + > time = local_clock(); > > - for_each_cpu_wrap(cpu, sched_domain_span(sd), target) { > + for_each_cpu_wrap(cpu, sched_domain_span(sd), target_tmp) { > + per_cpu(next_cpu, target) = cpu;
Is it possible that two simultaneous select_idle_cpu call have the same target value?
> if (!--nr) > return -1; > if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) >
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