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Groups > linux.kernel > #1633186 > unrolled thread
| Started by | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| First post | 2017-04-29 00:20 +0200 |
| Last post | 2017-05-02 15:40 +0200 |
| Articles | 3 — 2 participants |
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Re: [PATCH v2] sched/fair: update scale invariance of PELT Peter Zijlstra <peterz@infradead.org> - 2017-04-29 00:20 +0200
Re: [PATCH v2] sched/fair: update scale invariance of PELT Peter Zijlstra <peterz@infradead.org> - 2017-05-01 11:10 +0200
Re: [PATCH v2] sched/fair: update scale invariance of PELT Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-02 15:40 +0200
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Date | 2017-04-29 00:20 +0200 |
| Subject | Re: [PATCH v2] sched/fair: update scale invariance of PELT |
| Message-ID | <tBmp4-5t5-21@gated-at.bofh.it> |
On Mon, Apr 10, 2017 at 11:18:29AM +0200, Vincent Guittot wrote:
> +++ b/include/linux/sched.h
> @@ -313,6 +313,7 @@ struct load_weight {
> */
> struct sched_avg {
> u64 last_update_time;
> + u64 stolen_idle_time;
> u64 load_sum;
> u32 util_sum;
> u32 period_contrib;
> + if (sa->util_sum < (LOAD_AVG_MAX * 1000)) {
> + /*
> + * Add the idle time stolen by running at lower compute
> + * capacity
> + */
> + delta += sa->stolen_idle_time;
> + }
> + sa->stolen_idle_time = 0;
So I was wondering if stolen_idle_time really needs to be a u64. Afaict
we'll be at LOAD_AVG_MAX after LOAD_AVG_MAX_N periods, or LOAD_AVG_MAX_N
* LOAD_AVG_PERIOD time, which ends up being 11040.
After that you'll truncate it anyway.. so there shouldn't be a need to
be much larger than that, no?
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| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Date | 2017-05-01 11:10 +0200 |
| Message-ID | <tCfvd-7cA-29@gated-at.bofh.it> |
| In reply to | #1633186 |
On Sat, Apr 29, 2017 at 12:09:24AM +0200, Peter Zijlstra wrote:
> On Mon, Apr 10, 2017 at 11:18:29AM +0200, Vincent Guittot wrote:
> > +++ b/include/linux/sched.h
> > @@ -313,6 +313,7 @@ struct load_weight {
> > */
> > struct sched_avg {
> > u64 last_update_time;
> > + u64 stolen_idle_time;
> > u64 load_sum;
> > u32 util_sum;
> > u32 period_contrib;
>
> > + if (sa->util_sum < (LOAD_AVG_MAX * 1000)) {
> > + /*
> > + * Add the idle time stolen by running at lower compute
> > + * capacity
> > + */
> > + delta += sa->stolen_idle_time;
> > + }
> > + sa->stolen_idle_time = 0;
>
>
> So I was wondering if stolen_idle_time really needs to be a u64. Afaict
> we'll be at LOAD_AVG_MAX after LOAD_AVG_MAX_N periods, or LOAD_AVG_MAX_N
> * LOAD_AVG_PERIOD time, which ends up being 11040.
* 1024 or course, but still easily fits in u32.
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| From | Vincent Guittot <vincent.guittot@linaro.org> |
|---|---|
| Date | 2017-05-02 15:40 +0200 |
| Message-ID | <tCGc2-7i0-15@gated-at.bofh.it> |
| In reply to | #1633584 |
On 1 May 2017 at 11:00, Peter Zijlstra <peterz@infradead.org> wrote:
> On Sat, Apr 29, 2017 at 12:09:24AM +0200, Peter Zijlstra wrote:
>> On Mon, Apr 10, 2017 at 11:18:29AM +0200, Vincent Guittot wrote:
>> > +++ b/include/linux/sched.h
>> > @@ -313,6 +313,7 @@ struct load_weight {
>> > */
>> > struct sched_avg {
>> > u64 last_update_time;
>> > + u64 stolen_idle_time;
>> > u64 load_sum;
>> > u32 util_sum;
>> > u32 period_contrib;
>>
>> > + if (sa->util_sum < (LOAD_AVG_MAX * 1000)) {
>> > + /*
>> > + * Add the idle time stolen by running at lower compute
>> > + * capacity
>> > + */
>> > + delta += sa->stolen_idle_time;
>> > + }
>> > + sa->stolen_idle_time = 0;
>>
>>
>> So I was wondering if stolen_idle_time really needs to be a u64. Afaict
>> we'll be at LOAD_AVG_MAX after LOAD_AVG_MAX_N periods, or LOAD_AVG_MAX_N
>> * LOAD_AVG_PERIOD time, which ends up being 11040.
>
> * 1024 or course, but still easily fits in u32.
Correct
>
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