Messages in this thread | | | Date | Mon, 06 May 2013 15:20:36 +0800 | From | Michael Wang <> | Subject | Re: [PATCH v5 7/7] sched: consider runnable load average in effective_load |
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Hi, Preeti
On 05/06/2013 03:10 PM, Preeti U Murthy wrote: > Hi Alex,Michael, > > Can you try out the below patch and check?
Sure, I will take a try also.
I have the reason mentioned in the changelog. > If this also causes performance regression,you probably need to remove changes made in > effective_load() as Michael points out. I believe the below patch should not cause > performance regression.
Actually according to the current results of Alex's suggestion, I think the issue already addressed, anyway, I will test this patch and reply them at all, let's choose the best way later ;-)
Regards, Michael Wang
> > The below patch is a substitute for patch 7. > > > ------------------------------------------------------------------------------- > > sched: Modify effective_load() to use runnable load average > > From: Preeti U Murthy <preeti@linux.vnet.ibm.com> > > The runqueue weight distribution should update the runnable load average of > the cfs_rq on which the task will be woken up. > > However since the computation of se->load.weight takes into consideration > the runnable load average in update_cfs_shares(),no need to modify this in > effective_load(). > --- > kernel/sched/fair.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 790e23d..5489022 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -3045,7 +3045,7 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) > /* > * w = rw_i + @wl > */ > - w = se->my_q->load.weight + wl; > + w = se->my_q->runnable_load_avg + wl; > > /* > * wl = S * s'_i; see (2) > @@ -3066,6 +3066,9 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) > /* > * wl = dw_i = S * (s'_i - s_i); see (3) > */ > + /* Do not modify the below as it already contains runnable > + * load average in its computation > + */ > wl -= se->load.weight; > > /* > @@ -3112,14 +3115,14 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) > */ > if (sync) { > tg = task_group(current); > - weight = current->se.load.weight; > + weight = current->se.avg.load_avg_contrib; > > this_load += effective_load(tg, this_cpu, -weight, -weight); > load += effective_load(tg, prev_cpu, 0, -weight); > } > > tg = task_group(p); > - weight = p->se.load.weight; > + weight = p->se.avg.load_avg_contrib; > > /* > * In low-load situations, where prev_cpu is idle and this_cpu is idle > > > Regards > Preeti U Murthy > > On 05/06/2013 09:04 AM, Michael Wang wrote: >> Hi, Alex >> >> On 05/06/2013 09:45 AM, Alex Shi wrote: >>> effective_load calculates the load change as seen from the >>> root_task_group. It needs to engage the runnable average >>> of changed task. >> [snip] >>> */ >>> @@ -3045,7 +3045,7 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) >>> /* >>> * w = rw_i + @wl >>> */ >>> - w = se->my_q->load.weight + wl; >>> + w = se->my_q->tg_load_contrib + wl; >> >> I've tested the patch set, seems like the last patch caused big >> regression on pgbench: >> >> base patch 1~6 patch 1~7 >> | db_size | clients | tps | | tps | | tps | >> +---------+---------+-------+ +-------+ +-------+ >> | 22 MB | 32 | 43420 | | 53387 | | 41625 | >> >> I guess some magic thing happened in effective_load() while calculating >> group decay combined with load decay, what's your opinion? >> >> Regards, >> Michael Wang >> >>> >>> /* >>> * wl = S * s'_i; see (2) >>> @@ -3066,7 +3066,7 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) >>> /* >>> * wl = dw_i = S * (s'_i - s_i); see (3) >>> */ >>> - wl -= se->load.weight; >>> + wl -= se->avg.load_avg_contrib; >>> >>> /* >>> * Recursively apply this logic to all parent groups to compute >>> @@ -3112,14 +3112,14 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) >>> */ >>> if (sync) { >>> tg = task_group(current); >>> - weight = current->se.load.weight; >>> + weight = current->se.avg.load_avg_contrib; >>> >>> this_load += effective_load(tg, this_cpu, -weight, -weight); >>> load += effective_load(tg, prev_cpu, 0, -weight); >>> } >>> >>> tg = task_group(p); >>> - weight = p->se.load.weight; >>> + weight = p->se.avg.load_avg_contrib; >>> >>> /* >>> * In low-load situations, where prev_cpu is idle and this_cpu is idle >>> >> >
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