From 88a69dd7afd25f8ad3c6658cff5649cec2fad920 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 22 May 2012 14:04:28 +0200 Subject: [PATCH] --- yaml --- r: 310470 b: refs/heads/master c: b654f7de41b0e3903ee2b51d3b8db77fe52ce728 h: refs/heads/master v: v3 --- [refs] | 2 +- trunk/kernel/sched/fair.c | 15 +++++++++++---- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/[refs] b/[refs] index 425b534039d9..c6e9164f83e9 100644 --- a/[refs] +++ b/[refs] @@ -1,2 +1,2 @@ --- -refs/heads/master: 74a5ce20e6eeeb3751340b390e7ac1d1d07bbf55 +refs/heads/master: b654f7de41b0e3903ee2b51d3b8db77fe52ce728 diff --git a/trunk/kernel/sched/fair.c b/trunk/kernel/sched/fair.c index f0380d4987b3..2b449a762074 100644 --- a/trunk/kernel/sched/fair.c +++ b/trunk/kernel/sched/fair.c @@ -3503,15 +3503,22 @@ unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu) unsigned long scale_rt_power(int cpu) { struct rq *rq = cpu_rq(cpu); - u64 total, available; + u64 total, available, age_stamp, avg; - total = sched_avg_period() + (rq->clock - rq->age_stamp); + /* + * Since we're reading these variables without serialization make sure + * we read them once before doing sanity checks on them. + */ + age_stamp = ACCESS_ONCE(rq->age_stamp); + avg = ACCESS_ONCE(rq->rt_avg); + + total = sched_avg_period() + (rq->clock - age_stamp); - if (unlikely(total < rq->rt_avg)) { + if (unlikely(total < avg)) { /* Ensures that power won't end up being negative */ available = 0; } else { - available = total - rq->rt_avg; + available = total - avg; } if (unlikely((s64)total < SCHED_POWER_SCALE))