Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Thu, 28 Mar 2019 11:24:39 +0100 | Subject | Re: [PATCH v3 3/4] cpufreq: schedutil: Simplify iowait boosting |
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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
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