From fde7d22e01aa0d252fc5c95fa11f0dac35a4dd59 Mon Sep 17 00:00:00 2001 From: Yuyang Du Date: Tue, 13 Oct 2015 09:18:22 +0800 Subject: [PATCH] sched/fair: Fix overly small weight for interactive group entities Commit: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") led to an overly small weight for interactive group entities. The bad case can be easily reproduced when a number of CPU hogs compete for the CPUs at the same time (thanks to Mike). This is largly because the task group's load average tracking cross CPUs lags behind the real changes. To fix this we accelerate the group share distribution process by using the load.weight of the cfs_rq. This may increase the entire group's share, but we have to do so to protect the (fragile) interactive tasks, especially from CPU hogs. Reported-by: Mike Galbraith Tested-by: Dietmar Eggemann Tested-by: Mike Galbraith Signed-off-by: Yuyang Du Signed-off-by: Peter Zijlstra (Intel) Acked-by: Dietmar Eggemann Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1444699103-20272-1-git-send-email-yuyang.du@intel.com Signed-off-by: Ingo Molnar --- 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 6e2e3483b1ec..bc62c5096e54 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2363,7 +2363,7 @@ 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_avg(cfs_rq); + tg_weight += cfs_rq->load.weight; return tg_weight; } @@ -2373,7 +2373,7 @@ 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_avg(cfs_rq); + load = cfs_rq->load.weight; shares = (tg->shares * load); if (tg_weight)