On 27 July 2014 19:36, Yuyang Du <yuyang...@intel.com> wrote:
> Hi Vincent,
>
> On Fri, Jul 18, 2014 at 11:43:00AM +0200, Vincent Guittot wrote:
>> > @@ -2291,23 +2299,24 @@ static __always_inline int
>> > __update_entity_runnable_avg(u64 now,
>> > delta >>= 10;
>> > if (!delta)
>> > return 0;
>> > - sa->last_runnable_update = now;
>> > + sa->last_update_time = now;
>> >
>> > /* delta_w is the amount already accumulated against our next
>> > period */
>> > - delta_w = sa->runnable_avg_period % 1024;
>> > + delta_w = sa->period_contrib;
>> > if (delta + delta_w >= 1024) {
>> > - /* period roll-over */
>> > decayed = 1;
>> >
>> > + /* how much left for next period will start over, we don't
>> > know yet */
>> > + sa->period_contrib = 0;
>> > +
>> > /*
>> > * Now that we know we're crossing a period boundary,
>> > figure
>> > * out how much from delta we need to complete the current
>> > * period and accrue it.
>> > */
>> > delta_w = 1024 - delta_w;
>> > - if (runnable)
>> > - sa->runnable_avg_sum += delta_w;
>> > - sa->runnable_avg_period += delta_w;
>> > + if (w)
>> > + sa->load_sum += w * delta_w;
>>
>> Do you really need to have *w for computing the load_sum ? can't you
>> only use it when computing the load_avg ?
>>
>> sa->load_avg = div_u64(sa->load_sum * w , LOAD_AVG_MAX)
>>
>
> For task, assuming its load.weight does not change much, yes, we can. But in
> theory, task's
I would even say that the load_avg of a task should not be impacted by
an old priority value. Once, the priority of a task is changed, we
should only take into account this new priority to weight the load_avg
of the task
> load.weight can change, and *w in load_sum can take into that change. For
> group entity
> and cfs_rq, its load.weight changes all the time, I don't know how to do it
> without *w
> for load_sum.
IMHO, we should apply the same policy than the one i mentioned for
task. So the load_avg of an entity or a cfs_rq will not be disturbed
by an old but no more valid weight
Vincent
>
> Sorry for my irresponsiveness for last week. I was on vacation and
> unfortunately failed to
> connect VPN from where I was.
>
> Thanks,
> Yuyang
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