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Message-ID: <CAJZ5v0jR2RozeV301u4g90-BpNqkQMRrN=dgaOkJ7veVZ02=aw@mail.gmail.com> Date: Tue, 23 Aug 2022 20:04:49 +0200 From: "Rafael J. Wysocki" <rafael@...nel.org> To: Lukasz Luba <lukasz.luba@....com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...r.kernel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>, Vincent Guittot <vincent.guittot@...aro.org> Subject: Re: [PATCH v2] cpufreq: schedutil: Move max CPU capacity to sugov_policy On Tue, Aug 16, 2022 at 3:06 PM Lukasz Luba <lukasz.luba@....com> wrote: > > There is no need to keep the max CPU capacity in the per_cpu instance. > Furthermore, there is no need to check and update that variable > (sg_cpu->max) every time in the frequency change request, which is part > of hot path. Instead use struct sugov_policy to store that information. > Initialize the max CPU capacity during the setup and start callback. > We can do that since all CPUs in the same frequency domain have the same > max capacity (capacity setup and thermal pressure are based on that). > > Acked-by: Viresh Kumar <viresh.kumar@...aro.org> > Signed-off-by: Lukasz Luba <lukasz.luba@....com> > --- > Changes v2: > - collected ACK from Viresh > - re-based on top of latest mainline where the previously conflicting > change is now merged > > kernel/sched/cpufreq_schedutil.c | 30 +++++++++++++++--------------- > 1 file changed, 15 insertions(+), 15 deletions(-) > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > index 1207c78f85c1..9161d1136d01 100644 > --- a/kernel/sched/cpufreq_schedutil.c > +++ b/kernel/sched/cpufreq_schedutil.c > @@ -25,6 +25,9 @@ struct sugov_policy { > unsigned int next_freq; > unsigned int cached_raw_freq; > > + /* max CPU capacity, which is equal for all CPUs in freq. domain */ > + unsigned long max; > + > /* The next fields are only needed if fast switch cannot be used: */ > struct irq_work irq_work; > struct kthread_work work; > @@ -48,7 +51,6 @@ struct sugov_cpu { > > unsigned long util; > unsigned long bw_dl; > - unsigned long max; > > /* The field below is for single-CPU policies only: */ > #ifdef CONFIG_NO_HZ_COMMON > @@ -158,7 +160,6 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu) > { > struct rq *rq = cpu_rq(sg_cpu->cpu); > > - sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu); > sg_cpu->bw_dl = cpu_bw_dl(rq); > sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu), > FREQUENCY_UTIL, NULL); > @@ -253,6 +254,7 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, > */ > static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time) > { > + struct sugov_policy *sg_policy = sg_cpu->sg_policy; > unsigned long boost; > > /* No boost currently required */ > @@ -280,7 +282,8 @@ static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time) > * sg_cpu->util is already in capacity scale; convert iowait_boost > * into the same scale so we can compare. > */ > - boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT; > + boost = sg_cpu->iowait_boost * sg_policy->max; > + boost >>= SCHED_CAPACITY_SHIFT; > boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL); > if (sg_cpu->util < boost) > sg_cpu->util = boost; > @@ -337,7 +340,7 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time, > if (!sugov_update_single_common(sg_cpu, time, flags)) > return; > > - next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max); > + next_f = get_next_freq(sg_policy, sg_cpu->util, sg_policy->max); > /* > * Do not reduce the frequency if the CPU has not been idle > * recently, as the reduction is likely to be premature then. > @@ -373,6 +376,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time, > unsigned int flags) > { > struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util); > + struct sugov_policy *sg_policy = sg_cpu->sg_policy; > unsigned long prev_util = sg_cpu->util; > > /* > @@ -399,7 +403,8 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time, > sg_cpu->util = prev_util; > > cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl), > - map_util_perf(sg_cpu->util), sg_cpu->max); > + map_util_perf(sg_cpu->util), > + sg_policy->max); > > sg_cpu->sg_policy->last_freq_update_time = time; > } > @@ -408,25 +413,19 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time) > { > struct sugov_policy *sg_policy = sg_cpu->sg_policy; > struct cpufreq_policy *policy = sg_policy->policy; > - unsigned long util = 0, max = 1; > + unsigned long util = 0; > unsigned int j; > > for_each_cpu(j, policy->cpus) { > struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j); > - unsigned long j_util, j_max; > > sugov_get_util(j_sg_cpu); > sugov_iowait_apply(j_sg_cpu, time); > - j_util = j_sg_cpu->util; > - j_max = j_sg_cpu->max; > > - if (j_util * max > j_max * util) { > - util = j_util; > - max = j_max; > - } > + util = max(j_sg_cpu->util, util); > } > > - return get_next_freq(sg_policy, util, max); > + return get_next_freq(sg_policy, util, sg_policy->max); > } > > static void > @@ -752,7 +751,7 @@ static int sugov_start(struct cpufreq_policy *policy) > { > struct sugov_policy *sg_policy = policy->governor_data; > void (*uu)(struct update_util_data *data, u64 time, unsigned int flags); > - unsigned int cpu; > + unsigned int cpu = cpumask_first(policy->cpus); > > sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC; > sg_policy->last_freq_update_time = 0; > @@ -760,6 +759,7 @@ static int sugov_start(struct cpufreq_policy *policy) > sg_policy->work_in_progress = false; > sg_policy->limits_changed = false; > sg_policy->cached_raw_freq = 0; > + sg_policy->max = arch_scale_cpu_capacity(cpu); > > sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS); > > -- Applied as 6.1 material, thanks!
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