Messages in this thread Patch in this message | | | Date | Sat, 4 Feb 2023 18:42:31 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH 2/2 v5] sched/fair: Remove capacity inversion detection |
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On 02/01/23 15:36, Vincent Guittot wrote: > Remove the capacity inversion detection which is now handled by > util_fits_cpu() returning -1 when we need to continue to look for a > potential CPU with better performance. > > This ends up almost reverting patches below except for some comments:
nit: I think this comment must be removed/reworeded though
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 691a2f9c4efa..c6c8e7f52935 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4476,10 +4476,6 @@ static inline int util_fits_cpu(unsigned long util, * * For uclamp_max, we can tolerate a drop in performance level as the * goal is to cap the task. So it's okay if it's getting less. - * - * In case of capacity inversion, which is not handled yet, we should - * honour the inverted capacity for both uclamp_min and uclamp_max all - * the time. */ capacity_orig = capacity_orig_of(cpu); capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu); > commit da07d2f9c153 ("sched/fair: Fixes for capacity inversion detection") > commit aa69c36f31aa ("sched/fair: Consider capacity inversion in util_fits_cpu()") > commit 44c7b80bffc3 ("sched/fair: Detect capacity inversion") > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Apart from that, LGTM.
Reviewed-by: Qais Yousef <qyousef@layalina.io>
Thanks!
-- Qais Yousef
> --- > kernel/sched/fair.c | 84 +++----------------------------------------- > kernel/sched/sched.h | 19 ---------- > 2 files changed, 5 insertions(+), 98 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 074742f107c0..c6c8e7f52935 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4476,17 +4476,9 @@ static inline int util_fits_cpu(unsigned long util, > * > * For uclamp_max, we can tolerate a drop in performance level as the > * goal is to cap the task. So it's okay if it's getting less. > - * > - * In case of capacity inversion we should honour the inverted capacity > - * for both uclamp_min and uclamp_max all the time. > */ > - capacity_orig = cpu_in_capacity_inversion(cpu); > - if (capacity_orig) { > - capacity_orig_thermal = capacity_orig; > - } else { > - capacity_orig = capacity_orig_of(cpu); > - capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu); > - } > + capacity_orig = capacity_orig_of(cpu); > + capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu); > > /* > * We want to force a task to fit a cpu as implied by uclamp_max. > @@ -9027,82 +9019,16 @@ static unsigned long scale_rt_capacity(int cpu) > > static void update_cpu_capacity(struct sched_domain *sd, int cpu) > { > - unsigned long capacity_orig = arch_scale_cpu_capacity(cpu); > unsigned long capacity = scale_rt_capacity(cpu); > struct sched_group *sdg = sd->groups; > - struct rq *rq = cpu_rq(cpu); > > - rq->cpu_capacity_orig = capacity_orig; > + cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu); > > if (!capacity) > capacity = 1; > > - rq->cpu_capacity = capacity; > - > - /* > - * Detect if the performance domain is in capacity inversion state. > - * > - * Capacity inversion happens when another perf domain with equal or > - * lower capacity_orig_of() ends up having higher capacity than this > - * domain after subtracting thermal pressure. > - * > - * We only take into account thermal pressure in this detection as it's > - * the only metric that actually results in *real* reduction of > - * capacity due to performance points (OPPs) being dropped/become > - * unreachable due to thermal throttling. > - * > - * We assume: > - * * That all cpus in a perf domain have the same capacity_orig > - * (same uArch). > - * * Thermal pressure will impact all cpus in this perf domain > - * equally. > - */ > - if (sched_energy_enabled()) { > - unsigned long inv_cap = capacity_orig - thermal_load_avg(rq); > - struct perf_domain *pd; > - > - rcu_read_lock(); > - > - pd = rcu_dereference(rq->rd->pd); > - rq->cpu_capacity_inverted = 0; > - > - for (; pd; pd = pd->next) { > - struct cpumask *pd_span = perf_domain_span(pd); > - unsigned long pd_cap_orig, pd_cap; > - > - /* We can't be inverted against our own pd */ > - if (cpumask_test_cpu(cpu_of(rq), pd_span)) > - continue; > - > - cpu = cpumask_any(pd_span); > - pd_cap_orig = arch_scale_cpu_capacity(cpu); > - > - if (capacity_orig < pd_cap_orig) > - continue; > - > - /* > - * handle the case of multiple perf domains have the > - * same capacity_orig but one of them is under higher > - * thermal pressure. We record it as capacity > - * inversion. > - */ > - if (capacity_orig == pd_cap_orig) { > - pd_cap = pd_cap_orig - thermal_load_avg(cpu_rq(cpu)); > - > - if (pd_cap > inv_cap) { > - rq->cpu_capacity_inverted = inv_cap; > - break; > - } > - } else if (pd_cap_orig > inv_cap) { > - rq->cpu_capacity_inverted = inv_cap; > - break; > - } > - } > - > - rcu_read_unlock(); > - } > - > - trace_sched_cpu_capacity_tp(rq); > + cpu_rq(cpu)->cpu_capacity = capacity; > + trace_sched_cpu_capacity_tp(cpu_rq(cpu)); > > sdg->sgc->capacity = capacity; > sdg->sgc->min_capacity = capacity; > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 1072502976df..3e8df6d31c1e 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -1044,7 +1044,6 @@ struct rq { > > unsigned long cpu_capacity; > unsigned long cpu_capacity_orig; > - unsigned long cpu_capacity_inverted; > > struct balance_callback *balance_callback; > > @@ -2899,24 +2898,6 @@ static inline unsigned long capacity_orig_of(int cpu) > return cpu_rq(cpu)->cpu_capacity_orig; > } > > -/* > - * Returns inverted capacity if the CPU is in capacity inversion state. > - * 0 otherwise. > - * > - * Capacity inversion detection only considers thermal impact where actual > - * performance points (OPPs) gets dropped. > - * > - * Capacity inversion state happens when another performance domain that has > - * equal or lower capacity_orig_of() becomes effectively larger than the perf > - * domain this CPU belongs to due to thermal pressure throttling it hard. > - * > - * See comment in update_cpu_capacity(). > - */ > -static inline unsigned long cpu_in_capacity_inversion(int cpu) > -{ > - return cpu_rq(cpu)->cpu_capacity_inverted; > -} > - > /** > * enum cpu_util_type - CPU utilization type > * @FREQUENCY_UTIL: Utilization used to select frequency > -- > 2.34.1 >
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