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Groups > linux.kernel > #1358986
| From | "Rafael J. Wysocki" <rafael@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util |
| Date | 2016-03-16 14:30 +0100 |
| Message-ID | <rdjGp-136-9@gated-at.bofh.it> (permalink) |
| References | (4 earlier) <rdeno-5MN-13@gated-at.bofh.it> <rdf9M-6p0-7@gated-at.bofh.it> <rdft8-6zO-11@gated-at.bofh.it> <rdiU2-vS-9@gated-at.bofh.it> <rdjwK-YM-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Mar 16, 2016 at 2:10 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Mar 16, 2016 at 01:39:10PM +0100, Rafael J. Wysocki wrote:
>> On Wed, Mar 16, 2016 at 9:53 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>> > On Wed, Mar 16, 2016 at 09:29:59AM +0100, Vincent Guittot wrote:
>> >> I wonder if it's really worth passing per sched_class request to
>> >> sched_util ? sched_util is about selecting a frequency based on the
>> >> utilization of the CPU, it only needs a value that reflect the whole
>> >> utilization. Can't we sum (or whatever the formula we want to apply)
>> >> utilizations before calling cpufreq_update_util
>> >
>> > So I've thought the same; but I'm conflicted, its a shame to compute
>> > anything if the call then doesn't do anything with it.
>> >
>> > And keeping a structure of all the various numbers to pass in also has
>> > cost of yet another cacheline to touch.
>>
>> In principle we can use high-order bits of util and max to encode the
>> information on where they come from.
>>
>> Of course, that translates to additional ifs in the governor, but I
>> guess they are unavoidable anyway.
>
> Another thing we can do, for as long as we have the indirect function
> call anyway, is stuff extra pointers in that same cacheline we pull the
> function from.
>
> Something like the below; there's room for 8 pointers (including the
> function pointer) in a cacheline.
>
> That would allow the callback to fetch whatever data it feels is
> required (could be all of it).
>
> We could also put a u64 *now = &rq->clock in, which would leave another
> 4 pointers for DL/RT support.
>
> And since we're then back to 1-2 arguments on the function, we can add a
> flags/mask field to indicate what changed (and if the function
> throttles, it can keep a mask of all that changed since last time it
> actually did something, or allow punching through the throttle if our
> minimum guarantee changes or whatnot).
>
> (this would of course require we allocate struct update_util_data with
> the proper alignment thingies etc..)
>
> Then again, maybe this is somewhat overboard :-)
I was thinking about something along these lines, but then I thought
that passing in registers would be more efficient.
One advantage I can see here is that we don't pass arguments that may
not be used by the callee.
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index ba49c9efd0b2..d34d75c5cc93 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -3236,8 +3236,10 @@ static inline unsigned long rlimit_max(unsigned int limit)
>
> #ifdef CONFIG_CPU_FREQ
> struct update_util_data {
> - void (*func)(struct update_util_data *data,
> - u64 time, unsigned long util, unsigned long max);
> + unsigned long *cfs_util_avg;
> + unsigned long *cfs_util_max;
> +
> + void (*func)(struct update_util_data *data, u64 time);
> };
How do we ensure proper alignment?
> void cpufreq_set_update_util_data(int cpu, struct update_util_data *data);
> diff --git a/kernel/sched/cpufreq.c b/kernel/sched/cpufreq.c
> index 928c4ba32f68..de5b20b11de3 100644
> --- a/kernel/sched/cpufreq.c
> +++ b/kernel/sched/cpufreq.c
> @@ -32,6 +32,9 @@ void cpufreq_set_update_util_data(int cpu, struct update_util_data *data)
> if (WARN_ON(data && !data->func))
> return;
>
> + data->cfs_util_avg = &cpu_rq(cpu)->cfs.avg.util_avg;
> + data->cfs_util_max = &cpu_rq(cpu)->cpu_capacity_orig;
> +
> rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
> }
> EXPORT_SYMBOL_GPL(cpufreq_set_update_util_data);
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 0/8] schedutil enhancements Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
[PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:30 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:50 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Steve Muckle <steve.muckle@linaro.org> - 2016-03-16 04:40 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Peter Zijlstra <peterz@infradead.org> - 2016-03-16 09:10 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Juri Lelli <Juri.Lelli@arm.com> - 2016-03-16 11:10 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Steve Muckle <steve.muckle@linaro.org> - 2016-03-16 19:00 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Michael Turquette <mturquette@baylibre.com> - 2016-03-16 23:10 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Juri Lelli <Juri.Lelli@arm.com> - 2016-03-17 10:40 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Steve Muckle <steve.muckle@linaro.org> - 2016-03-17 15:00 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Patrick Bellasi <patrick.bellasi@arm.com> - 2016-03-17 17:00 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-16 13:50 +0100
Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Michael Turquette <mturquette@baylibre.com> - 2016-03-16 23:10 +0100
[PATCH 1/8] sched/cpufreq: remove cpufreq_trigger_update() Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
Re: [PATCH 1/8] sched/cpufreq: remove cpufreq_trigger_update() Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:20 +0100
Re: [PATCH 1/8] sched/cpufreq: remove cpufreq_trigger_update() Peter Zijlstra <peterz@infradead.org> - 2016-03-15 23:00 +0100
Re: [PATCH 1/8] sched/cpufreq: remove cpufreq_trigger_update() Peter Zijlstra <peterz@infradead.org> - 2016-03-16 09:10 +0100
[PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:30 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Steve Muckle <steve.muckle@linaro.org> - 2016-03-16 05:00 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Peter Zijlstra <peterz@infradead.org> - 2016-03-16 08:50 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-16 09:40 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Peter Zijlstra <peterz@infradead.org> - 2016-03-16 10:00 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-16 10:20 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-16 13:40 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Peter Zijlstra <peterz@infradead.org> - 2016-03-16 14:20 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-16 14:30 +0100
Re: [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Peter Zijlstra <peterz@infradead.org> - 2016-03-16 14:50 +0100
[PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-03-15 20:20 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Michael Turquette <mturquette@baylibre.com> - 2016-03-15 21:50 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-03-16 20:50 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Peter Zijlstra <peterz@infradead.org> - 2016-03-16 21:10 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-16 22:40 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:50 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Peter Zijlstra <peterz@infradead.org> - 2016-03-16 08:50 +0100
Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Peter Zijlstra <peterz@infradead.org> - 2016-03-16 13:50 +0100
[PATCH 2/8] sched/fair: add margin to utilization update Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
Re: [PATCH 2/8] sched/fair: add margin to utilization update Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:20 +0100
Re: [PATCH 2/8] sched/fair: add margin to utilization update Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:50 +0100
Re: [PATCH 2/8] sched/fair: add margin to utilization update Steve Muckle <steve.muckle@linaro.org> - 2016-03-16 04:00 +0100
Re: [PATCH 2/8] sched/fair: add margin to utilization update Michael Turquette <mturquette@baylibre.com> - 2016-03-16 23:20 +0100
[PATCH 3/8] sched/cpufreq: new cfs capacity margin helpers Michael Turquette <mturquette@baylibre.com> - 2016-03-14 06:30 +0100
Re: [PATCH 3/8] sched/cpufreq: new cfs capacity margin helpers Peter Zijlstra <peterz@infradead.org> - 2016-03-15 22:20 +0100
Re: [PATCH 0/8] schedutil enhancements "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-16 01:10 +0100
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