| Message ID | 1572979786-20361-5-git-send-email-thara.gopinath@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce Thermal Pressure | expand |
On 11/05/19 13:49, 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. > > Other signals that are deducted from cpu_capacity to reflect the actual > capacity available are rt and dl util_avg. util_avg tracks a binary signal > and uses the weights 1024 and 0. Whereas thermal pressure is tracked > using load_avg. load_avg uses the actual "delta" capacity as the weight. I think you intended to put this as comment... > > 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 9fb0494..5f6c371 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7738,6 +7738,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, 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); ... here? I find the explanation hard to parse too. Do you think you can rephrase it? Something based on what you wrote here would be more understandable IMHO: https://lore.kernel.org/lkml/5DBB05BC.40502@linaro.org/ Thanks! -- Qais Yousef > > if (unlikely(used >= max)) > return 1; > -- > 2.1.4 >
On 11/06/2019 11:56 AM, Qais Yousef wrote: > On 11/05/19 13:49, 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. >> >> Other signals that are deducted from cpu_capacity to reflect the actual >> capacity available are rt and dl util_avg. util_avg tracks a binary signal >> and uses the weights 1024 and 0. Whereas thermal pressure is tracked >> using load_avg. load_avg uses the actual "delta" capacity as the weight. > > I think you intended to put this as comment... > >> >> 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 9fb0494..5f6c371 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -7738,6 +7738,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, 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); > > ... here? I did not! But I can. > > I find the explanation hard to parse too. Do you think you can rephrase it? > Something based on what you wrote here would be more understandable IMHO: > https://lore.kernel.org/lkml/5DBB05BC.40502@linaro.org/ I will try to rephrase it! I am sorry that you found it hard to parse. Honestly, I cannot copy paste the code snippet I pointed out to you here in comment.(And I think that is the reason you found it easier to understand) But I will try my best to put it in words. > > > Thanks! > > -- > Qais Yousef > >> >> if (unlikely(used >= max)) >> return 1; >> -- >> 2.1.4 >> -- Warm Regards Thara
On 11/06/19 12:31, Thara Gopinath wrote: > On 11/06/2019 11:56 AM, Qais Yousef wrote: > > On 11/05/19 13:49, 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. > >> > >> Other signals that are deducted from cpu_capacity to reflect the actual > >> capacity available are rt and dl util_avg. util_avg tracks a binary signal > >> and uses the weights 1024 and 0. Whereas thermal pressure is tracked > >> using load_avg. load_avg uses the actual "delta" capacity as the weight. > > > > I think you intended to put this as comment... > > > >> > >> 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 9fb0494..5f6c371 100644 > >> --- a/kernel/sched/fair.c > >> +++ b/kernel/sched/fair.c > >> @@ -7738,6 +7738,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, 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); > > > > ... here? > > I did not! But I can. > > > > I find the explanation hard to parse too. Do you think you can rephrase it? > > Something based on what you wrote here would be more understandable IMHO: > > https://lore.kernel.org/lkml/5DBB05BC.40502@linaro.org/ > I will try to rephrase it! I am sorry that you found it hard to parse. > Honestly, I cannot copy paste the code snippet I pointed out to you here > in comment.(And I think that is the reason you found it easier to > understand) But I will try my best to put it in words. No worries. The problem could be me :-) But a comment in the code is very important as util_avg + load_avg is confusing without a comment. I wouldn't expect both signal to be compatible but the thermal one is special. A comment explaining why it's special is all we need. Thanks -- Qais Yousef
On Wed, Nov 6, 2019 at 12:20 AM Thara Gopinath <thara.gopinath@linaro.org> wrote: > > cpu_capacity relflects the maximum available capacity of a cpu. Thermal s/relflects/reflects > 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. > > Other signals that are deducted from cpu_capacity to reflect the actual > capacity available are rt and dl util_avg. util_avg tracks a binary signal > and uses the weights 1024 and 0. Whereas thermal pressure is tracked > using load_avg. load_avg uses the actual "delta" capacity as the weight. Consider rephrasing as, Currently, effective cpu capacity is calculated by deducting RT and DL average utilization (util_avg) from cpu_capacity. For thermal pressure, we use load_avg instead of util_avg which is a binary signal (0 or 1024) because <put why here> > 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 9fb0494..5f6c371 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7738,6 +7738,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, 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; > -- > 2.1.4 >
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9fb0494..5f6c371 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7738,6 +7738,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, 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. Other signals that are deducted from cpu_capacity to reflect the actual capacity available are rt and dl util_avg. util_avg tracks a binary signal and uses the weights 1024 and 0. Whereas thermal pressure is tracked using load_avg. load_avg uses the actual "delta" capacity as the weight. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> --- kernel/sched/fair.c | 1 + 1 file changed, 1 insertion(+) -- 2.1.4