Commit-ID: 3d89e5478bf550a50c99e93adf659369798263b0
Gitweb: http://git.kernel.org/tip/3d89e5478bf550a50c99e93adf659369798263b0
Author: Wanpeng Li <wanpeng...@hotmail.com>
AuthorDate: Mon, 13 Jun 2016 18:32:45 +0800
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Tue, 14 Jun 2016 11:13:15 +0200
sched/cputime: Fix prev steal time accouting during CPU hotplug
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 <wanpeng...@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Acked-by: Paolo Bonzini <pbonz...@redhat.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Radim Krčmář <rkrc...@redhat.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
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...@hotmail.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
kernel/sched/core.c | 1 -
kernel/sched/sched.h | 13 -------------
2 files changed, 14 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 13d0896..c1b537b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7227,7 +7227,6 @@ static void sched_rq_cpu_starting(unsigned int cpu)
struct rq *rq = cpu_rq(cpu);
rq->calc_load_update = calc_load_update;
- account_reset_rq(rq);
update_max_interval();
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 72f1f30..de607e4 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1809,16 +1809,3 @@ static inline void cpufreq_trigger_update(u64 time) {}
#else /* arch_scale_freq_capacity */
#define arch_scale_freq_invariant() (false)
#endif
-
-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
-}
