From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Quentin Perret <quentin.perret@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Chen Yu <yu.c.chen@intel.com>,
Gabriele Mazzotta <gabriele.mzt@gmail.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 3/4] cpufreq: schedutil: Simplify iowait boosting
Date: Thu, 28 Mar 2019 11:24:39 +0100 [thread overview]
Message-ID: <CAJZ5v0jx6ZsYaq=YtYfGFDACkT4Gg=mf+hSBOT_RQeMo7AaM3w@mail.gmail.com> (raw)
In-Reply-To: <20190328094823.y6gyfb6ldq43gojw@queper01-lin>
On Thu, Mar 28, 2019 at 10:48 AM Quentin Perret <quentin.perret@arm.com> wrote:
>
> Hi Rafael,
>
> On Tuesday 26 Mar 2019 at 12:18:00 (+0100), Rafael J. Wysocki wrote:
> > @@ -13,6 +13,8 @@
> > #include <linux/sched/cpufreq.h>
> > #include <trace/events/power.h>
> >
> > +#define IOWAIT_BOOST_MIN (SCHED_CAPACITY_SCALE / 8)
> > +
> > struct sugov_tunables {
> > struct gov_attr_set attr_set;
> > unsigned int rate_limit_us;
> > @@ -51,7 +53,6 @@ struct sugov_cpu {
> > u64 last_update;
> >
> > unsigned long bw_dl;
> > - unsigned long min;
> > unsigned long max;
> >
> > /* The field below is for single-CPU policies only: */
> > @@ -303,7 +304,7 @@ static bool sugov_iowait_reset(struct sua
>
> The comment above this function needs updating I think.
>
> > if (delta_ns <= TICK_NSEC)
> > return false;
> >
> > - sg_cpu->iowait_boost = set_iowait_boost ? sg_cpu->min : 0;
> > + sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
> > sg_cpu->iowait_boost_pending = set_iowait_boost;
> >
> > return true;
> > @@ -349,7 +350,7 @@ static void sugov_iowait_boost(struct su
>
> Ditto.
I overlooked these two, thanks for pointing that out!
Will send an update momentarily.
> > }
> >
> > /* First wakeup after IO: start with minimum boost */
> > - sg_cpu->iowait_boost = sg_cpu->min;
> > + sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
> > }
> >
> > /**
> > @@ -389,7 +390,7 @@ static unsigned long sugov_iowait_apply(
> > * No boost pending; reduce the boost value.
> > */
> > sg_cpu->iowait_boost >>= 1;
> > - if (sg_cpu->iowait_boost < sg_cpu->min) {
> > + if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
> > sg_cpu->iowait_boost = 0;
> > return util;
> > }
> > @@ -826,9 +827,6 @@ static int sugov_start(struct cpufreq_po
> > memset(sg_cpu, 0, sizeof(*sg_cpu));
> > sg_cpu->cpu = cpu;
> > sg_cpu->sg_policy = sg_policy;
> > - sg_cpu->min =
> > - (SCHED_CAPACITY_SCALE * policy->cpuinfo.min_freq) /
> > - policy->cpuinfo.max_freq;
> > }
> >
> > for_each_cpu(cpu, policy->cpus) {
> >
>
> Other than that, I tried a backport of this on a Pixel 3 with Snapdragon
> 845 (which is relevant because it has tons of OPPs, so starting at 128
> makes it ramp up faster) to check the impact on power, but the only
> differences appeared to be in the noise margin, so it's all good :)
Cool. :-)
> Full test results available at [1]. Note that I did enable the iowait
> boost feature for these tests -- it is disabled by default on P3 ...
Thanks!
> ---
> [1] https://nbviewer.jupyter.org/gist/qperret/69c9bde13aad2d783689e78c9ba2d9bc
next prev parent reply other threads:[~2019-03-28 10:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 11:12 [PATCH v3 0/4] cpufreq: intel_pstate: Handle _PPC updates on global turbo disable/enable Rafael J. Wysocki
2019-03-26 11:15 ` [PATCH v3 1/4] cpufreq: intel_pstate: Driver-specific handling of _PPC updates Rafael J. Wysocki
2019-03-26 11:16 ` [PATCH v3 2/4] cpufreq: Add cpufreq_cpu_acquire() and cpufreq_cpu_release() Rafael J. Wysocki
2019-03-26 11:18 ` [PATCH v3 3/4] cpufreq: schedutil: Simplify iowait boosting Rafael J. Wysocki
2019-03-28 9:48 ` Quentin Perret
2019-03-28 10:24 ` Rafael J. Wysocki [this message]
2019-03-28 10:33 ` [Update][PATCH " Rafael J. Wysocki
2019-04-01 9:27 ` Rafael J. Wysocki
2019-04-01 10:29 ` Peter Zijlstra
2019-04-08 5:54 ` Viresh Kumar
2019-03-26 11:19 ` [PATCH v3 4/4] cpufreq: intel_pstate: Update max frequency on global turbo changes Rafael J. Wysocki
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