From 62208707b466cc3c6ce951a7c4b7b4bb9b9192f6 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 13 Jun 2016 18:32:45 +0800 Subject: sched/cputime: Fix prev steal time accouting during CPU hotplug MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 3d89e5478bf550a50c99e93adf659369798263b0 upstream. Commit: e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug") ... set rq->prev_* to 0 after a CPU hotplug comes back, in order to fix the case where (after CPU hotplug) steal time is smaller than rq->prev_steal_time. However, this should never happen. Steal time was only smaller because of the KVM-specific bug fixed by the previous patch. Worse, the previous patch triggers a bug on CPU hot-unplug/plug operation: because rq->prev_steal_time is cleared, all of the CPU's past steal time will be accounted again on hot-plug. Since the root cause has been fixed, we can just revert commit e9532e69b8d1. Signed-off-by: Wanpeng Li Signed-off-by: Peter Zijlstra (Intel) Acked-by: Paolo Bonzini Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Radim Krčmář Cc: Rik van Riel Cc: Thomas Gleixner Fixes: 'commit e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")' Link: http://lkml.kernel.org/r/1465813966-3116-3-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar Signed-off-by: Andres Oportus Acked-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- kernel/sched/core.c | 1 - kernel/sched/sched.h | 13 ------------- 2 files changed, 14 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 47368c6d26f8..dece705b7f8c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5553,7 +5553,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) case CPU_UP_PREPARE: rq->calc_load_update = calc_load_update; - account_reset_rq(rq); break; case CPU_ONLINE: diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4e5db65d1aab..55d92a1ca070 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1770,16 +1770,3 @@ static inline u64 irq_time_read(int cpu) } #endif /* CONFIG_64BIT */ #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ - -static inline void account_reset_rq(struct rq *rq) -{ -#ifdef CONFIG_IRQ_TIME_ACCOUNTING - rq->prev_irq_time = 0; -#endif -#ifdef CONFIG_PARAVIRT - rq->prev_steal_time = 0; -#endif -#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING - rq->prev_steal_time_rq = 0; -#endif -} -- cgit v1.2.3