| Message ID | 1366910611-20048-5-git-send-email-vincent.guittot@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Apr 25, 2013 at 07:23:20PM +0200, Vincent Guittot wrote: > Look for an idle CPU close to the pack buddy CPU whenever possible. > The goal is to prevent the wake up of a CPU which doesn't share the power > domain of the pack buddy CPU. > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > Reviewed-by: Morten Rasmussen <morten.rasmussen@arm.com> > --- > kernel/sched/fair.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 6adc57c..a985c98 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5469,7 +5469,26 @@ static struct { > > static inline int find_new_ilb(int call_cpu) > { > + struct sched_domain *sd; > int ilb = cpumask_first(nohz.idle_cpus_mask); > + int buddy = per_cpu(sd_pack_buddy, call_cpu); > + > + /* > + * If we have a pack buddy CPU, we try to run load balance on a CPU > + * that is close to the buddy. > + */ > + if (buddy != -1) { > + for_each_domain(buddy, sd) { > + if (sd->flags & SD_SHARE_CPUPOWER) > + continue; > + > + ilb = cpumask_first_and(sched_domain_span(sd), > + nohz.idle_cpus_mask); > + > + if (ilb < nr_cpu_ids) > + break; > + } > + } > > if (ilb < nr_cpu_ids && idle_cpu(ilb)) > return ilb; Ha! and here you hope people won't put multiple big-little clusters in a single machine? :-)
On 26 April 2013 14:49, Peter Zijlstra <peterz@infradead.org> wrote: > On Thu, Apr 25, 2013 at 07:23:20PM +0200, Vincent Guittot wrote: >> Look for an idle CPU close to the pack buddy CPU whenever possible. >> The goal is to prevent the wake up of a CPU which doesn't share the power >> domain of the pack buddy CPU. >> >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> >> Reviewed-by: Morten Rasmussen <morten.rasmussen@arm.com> >> --- >> kernel/sched/fair.c | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 6adc57c..a985c98 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -5469,7 +5469,26 @@ static struct { >> >> static inline int find_new_ilb(int call_cpu) >> { >> + struct sched_domain *sd; >> int ilb = cpumask_first(nohz.idle_cpus_mask); >> + int buddy = per_cpu(sd_pack_buddy, call_cpu); >> + >> + /* >> + * If we have a pack buddy CPU, we try to run load balance on a CPU >> + * that is close to the buddy. >> + */ >> + if (buddy != -1) { >> + for_each_domain(buddy, sd) { >> + if (sd->flags & SD_SHARE_CPUPOWER) >> + continue; >> + >> + ilb = cpumask_first_and(sched_domain_span(sd), >> + nohz.idle_cpus_mask); >> + >> + if (ilb < nr_cpu_ids) >> + break; >> + } >> + } >> >> if (ilb < nr_cpu_ids && idle_cpu(ilb)) >> return ilb; > > Ha! and here you hope people won't put multiple big-little clusters in a single > machine? :-) yes, we will probably face this situation sooner or later but the other little clusters will probably be not less close than the local big cluster from a power domain point of view. That's why i look for the small sched_domain level to the largest one > > >
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6adc57c..a985c98 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5469,7 +5469,26 @@ static struct { static inline int find_new_ilb(int call_cpu) { + struct sched_domain *sd; int ilb = cpumask_first(nohz.idle_cpus_mask); + int buddy = per_cpu(sd_pack_buddy, call_cpu); + + /* + * If we have a pack buddy CPU, we try to run load balance on a CPU + * that is close to the buddy. + */ + if (buddy != -1) { + for_each_domain(buddy, sd) { + if (sd->flags & SD_SHARE_CPUPOWER) + continue; + + ilb = cpumask_first_and(sched_domain_span(sd), + nohz.idle_cpus_mask); + + if (ilb < nr_cpu_ids) + break; + } + } if (ilb < nr_cpu_ids && idle_cpu(ilb)) return ilb;