On Mon, 05 Dec, at 01:35:46PM, Matt Fleming wrote:
> On Mon, 05 Dec, at 10:27:36AM, Vincent Guittot wrote:
> >
> > Hi Matt,
> >
> > Thanks for the results.
> >
> > During the review, it has been pointed out by Morten that the test condition
> > (100*this_avg_load < imbalance_scale*min_avg_load) makes more sense than
> > (100*min_avg_load > imbalance_scale*this_avg_load). But i see lower
> > performances with this change. Coud you run tests with the change below on
> > top of the patchset ?
> >
> > ---
> > kernel/sched/fair.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index e8d1ae7..0129fbb 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -5514,7 +5514,7 @@ find_idlest_group(struct sched_domain *sd, struct
> > task_struct *p,
> > if (!idlest ||
> > (min_runnable_load > (this_runnable_load + imbalance)) ||
> > ((this_runnable_load < (min_runnable_load + imbalance)) &&
> > - (100*min_avg_load > imbalance_scale*this_avg_load)))
> > + (100*this_avg_load < imbalance_scale*min_avg_load)))
> > return NULL;
> > return idlest;
> > }
>
> Queued for testing.
Most of the machines didn't notice the difference with this new patch.
However, I did come across one test that showed a negative change,
hackbench-thread-pipes
4.9.0-rc6 4.9.0-rc6 4.9.0-rc6
4.9.0-rc6
tip-sched fix-fig-for-fork fix-sig
fix-fig-for-fork-v2
Amean 1 0.1266 ( 0.00%) 0.1269 ( -0.23%) 0.1287 ( -1.69%)
0.1357 ( -7.22%)
Amean 4 0.4989 ( 0.00%) 0.5174 ( -3.72%) 0.5251 ( -5.27%)
0.5117 ( -2.58%)
Amean 7 0.8510 ( 0.00%) 0.8517 ( -0.08%) 0.8964 ( -5.34%)
0.8801 ( -3.42%)
Amean 12 1.0699 ( 0.00%) 1.0484 ( 2.00%) 1.0147 ( 5.15%)
1.0759 ( -0.56%)
Amean 21 1.2816 ( 0.00%) 1.2140 ( 5.27%) 1.1879 ( 7.31%)
1.2414 ( 3.13%)
Amean 30 1.4440 ( 0.00%) 1.4003 ( 3.03%) 1.3969 ( 3.26%)
1.4057 ( 2.65%)
Amean 48 1.5773 ( 0.00%) 1.5983 ( -1.33%) 1.3984 ( 11.34%)
1.5624 ( 0.94%)
Amean 79 2.2343 ( 0.00%) 2.3066 ( -3.24%) 2.0053 ( 10.25%)
2.2630 ( -1.29%)
Amean 96 2.6736 ( 0.00%) 2.4313 ( 9.06%) 2.4181 ( 9.55%)
2.4717 ( 7.55%)
4.9.0-rc6 4.9.0-rc6 4.9.0-rc6 4.9.0-rc6
tip-schedfix-fig-for-fork fix-sigfix-fig-for-fork-v2
User 129.53 128.64 127.70 131.00
System 1784.54 1744.21 1654.08 1744.00
Elapsed 92.07 90.44 86.95 91.00
Looking at the 48 and 79 groups rows for mean there's a noticeable
drop off in performance of ~10%, which should be outside of the noise
for this test. This is a 2 socket, 4 NUMA node (yes, really), 24 cpus
AMD opteron circa 2010.
Given the age of this machine, I don't think it's worth holding up the
patch.
