From c9c294a630e28eec5f2865f028ecfc58d45c0a5a Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 27 Jun 2008 13:41:12 +0200 Subject: sched: fix calc_delta_asym() calc_delta_asym() is supposed to do the same as calc_delta_fair() except linearly shrink the result for negative nice processes - this causes them to have a smaller preemption threshold so that they are more easily preempted. The problem is that for task groups se->load.weight is the per cpu share of the actual task group weight; take that into account. Also provide a debug switch to disable the asymmetry (which I still don't like - but it does greatly benefit some workloads) This would explain the interactivity issues reported against group scheduling. Signed-off-by: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Mike Galbraith Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 28 +++++++++++++++++++++++++++- kernel/sched_features.h | 1 + 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 4965009..2268e63 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -430,6 +430,29 @@ calc_delta_asym(unsigned long delta, struct sched_entity *se) for_each_sched_entity(se) { struct load_weight *se_lw = &se->load; +#ifdef CONFIG_FAIR_SCHED_GROUP + struct cfs_rq *cfs_rq = se->my_q; + struct task_group *tg = NULL + + if (cfs_rq) + tg = cfs_rq->tg; + + if (tg && tg->shares < NICE_0_LOAD) { + /* + * scale shares to what it would have been had + * tg->weight been NICE_0_LOAD: + * + * weight = 1024 * shares / tg->weight + */ + lw.weight *= se->load.weight; + lw.weight /= tg->shares; + + lw.inv_weight = 0; + + se_lw = &lw; + } else +#endif + if (se->load.weight < NICE_0_LOAD) se_lw = &lw; @@ -1154,7 +1177,10 @@ static unsigned long wakeup_gran(struct sched_entity *se) * More easily preempt - nice tasks, while not making it harder for * + nice tasks. */ - gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se); + if (sched_feat(ASYM_GRAN)) + gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se); + else + gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se); return gran; } diff --git a/kernel/sched_features.h b/kernel/sched_features.h index afa5491..04123af 100644 --- a/kernel/sched_features.h +++ b/kernel/sched_features.h @@ -7,3 +7,4 @@ SCHED_FEAT(CACHE_HOT_BUDDY, 1) SCHED_FEAT(SYNC_WAKEUPS, 1) SCHED_FEAT(HRTICK, 1) SCHED_FEAT(DOUBLE_TICK, 0) +SCHED_FEAT(ASYM_GRAN, 1) -- cgit v1.1