Messages in this thread | | | From | Vincent Guittot <> | Date | Tue, 29 Jul 2014 11:12:37 +0200 | Subject | Re: [PATCH 2/2 v4] sched: Rewrite per entity runnable load average tracking |
| |
On 27 July 2014 19:36, Yuyang Du <yuyang.du@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
| |