Hi Peter, the proposed patch has fixed the performance issue. I have applied the patch to v4.7-rc4
Jirka On Fri, Jun 24, 2016 at 2:44 PM, Vincent Guittot <vincent.guit...@linaro.org> wrote: > Hi Peter, > > On 24 June 2016 at 14:02, Peter Zijlstra <pet...@infradead.org> wrote: >> On Fri, Jun 24, 2016 at 09:44:41AM +0200, Jirka Hladky wrote: >>> Hi Peter, >>> >>> thanks a lot for looking into it! >>> >>> I have tried to disable autogroups >>> >>> sysctl -w kernel.sched_autogroup_enabled=0 >>> >>> and I can confirm that performance is then back at level as in 4.6 kernel. >> >> So unless the heat has made me do really silly things, the below seems >> to cure things. Could you please verify? >> >> >> --- >> kernel/sched/fair.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 22d64b3f5876..d4f6fb2f3057 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -2484,7 +2484,7 @@ static inline long calc_tg_weight(struct task_group >> *tg, struct cfs_rq *cfs_rq) >> */ >> tg_weight = atomic_long_read(&tg->load_avg); >> tg_weight -= cfs_rq->tg_load_avg_contrib; >> - tg_weight += cfs_rq->load.weight; >> + tg_weight += cfs_rq->avg.load_avg; > > IIUC, you are reverting > commit fde7d22e01aa (sched/fair: Fix overly small weight for > interactive group entities) > > I have one question regarding the use of cfs_rq->avg.load_avg > cfs_rq->tg_load_avg_contrib is the sampling of cfs_rq->avg.load_avg so > I'm curious to understand why you use cfs_rq->avg.load_avg instead of > keeping cfs_rq->tg_load_avg_contrib. Do you think that the sampling is > not accurate enough to prevent any significant difference between both > when we use tg->load_avg ? > > >> >> return tg_weight; >> } >> @@ -2494,7 +2494,7 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, >> struct task_group *tg) >> long tg_weight, load, shares; >> >> tg_weight = calc_tg_weight(tg, cfs_rq); >> - load = cfs_rq->load.weight; >> + load = cfs_rq->avg.load_avg; >> >> shares = (tg->shares * load); >> if (tg_weight)
