| Message ID | 1539102302-9057-7-git-send-email-thara.gopinath@linaro.org (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | Introduce thermal pressure | expand |
On Tue, Oct 09, 2018 at 12:25:01PM -0400, Thara Gopinath wrote: > cpu_capacity relflects the maximum available capacity of a cpu. Thermal > pressure on a cpu means this maximum available capacity is reduced. This > patch reduces the average thermal pressure for a cpu from its maximum > available capacity so that cpu_capacity reflects the actual > available capacity. > > Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> > --- > kernel/sched/fair.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 7deb1d0..8651e55 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7497,6 +7497,7 @@ static unsigned long scale_rt_capacity(int cpu) > > used = READ_ONCE(rq->avg_rt.util_avg); > used += READ_ONCE(rq->avg_dl.util_avg); > + used += READ_ONCE(rq->avg_thermal.load_avg); IIUIC, you are treating thermal pressure as an artificial load on the cpu. If so, this sounds like a hard to maintain hack. Thermal pressure have different characteristics to utilization. What happens if thermal sets the cpu cooling state back to 0 because there is thermal headroom again? Do we keep adding this artificial load to the cpu just because there was thermal pressure in the past and let it decay as if it was cpu load? Cheers, Javi
On 10/10/2018 01:57 AM, Javi Merino wrote: > On Tue, Oct 09, 2018 at 12:25:01PM -0400, Thara Gopinath wrote: >> cpu_capacity relflects the maximum available capacity of a cpu. Thermal >> pressure on a cpu means this maximum available capacity is reduced. This >> patch reduces the average thermal pressure for a cpu from its maximum >> available capacity so that cpu_capacity reflects the actual >> available capacity. >> >> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> >> --- >> kernel/sched/fair.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 7deb1d0..8651e55 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -7497,6 +7497,7 @@ static unsigned long scale_rt_capacity(int cpu) >> >> used = READ_ONCE(rq->avg_rt.util_avg); >> used += READ_ONCE(rq->avg_dl.util_avg); >> + used += READ_ONCE(rq->avg_thermal.load_avg); > > IIUIC, you are treating thermal pressure as an artificial load on the > cpu. If so, this sounds like a hard to maintain hack. Thermal > pressure have different characteristics to utilization. What happens > if thermal sets the cpu cooling state back to 0 because there is > thermal headroom again? Do we keep adding this artificial load to the > cpu just because there was thermal pressure in the past and let it > decay as if it was cpu load? Setting cpu cooling state back to 0 will decay the thermal pressure back to 0 ? Yes, cpu will not register an instantaneous drop in the cap, it will be decayed down following the PELT signals. > > Cheers, > Javi >
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7deb1d0..8651e55 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7497,6 +7497,7 @@ static unsigned long scale_rt_capacity(int cpu) used = READ_ONCE(rq->avg_rt.util_avg); used += READ_ONCE(rq->avg_dl.util_avg); + used += READ_ONCE(rq->avg_thermal.load_avg); if (unlikely(used >= max)) return 1;
cpu_capacity relflects the maximum available capacity of a cpu. Thermal pressure on a cpu means this maximum available capacity is reduced. This patch reduces the average thermal pressure for a cpu from its maximum available capacity so that cpu_capacity reflects the actual available capacity. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> --- kernel/sched/fair.c | 1 + 1 file changed, 1 insertion(+)