summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorWanpeng Li <wanpeng.li@hotmail.com>2016-08-11 05:36:35 (GMT)
committerIngo Molnar <mingo@kernel.org>2016-08-11 09:02:14 (GMT)
commitf9bcf1e0e0145323ba2cf72ecad5264ff3883eb1 (patch)
treea91de94c46cb85a38fb8198ee2c65e37e4bb8347
parentc0c8c9fa210c9a042060435f17e40ba4a76d6d6f (diff)
downloadlinux-f9bcf1e0e0145323ba2cf72ecad5264ff3883eb1.tar.xz
sched/cputime: Fix steal time accounting
Commit: 57430218317 ("sched/cputime: Count actually elapsed irq & softirq time") ... didn't take steal time into consideration with passing the noirqtime kernel parameter. As Paolo pointed out before: | Why not? If idle=poll, for example, any time the guest is suspended (and | thus cannot poll) does count as stolen time. This patch fixes it by reducing steal time from idle time accounting when the noirqtime parameter is true. The average idle time drops from 56.8% to 54.75% for nohz idle kvm guest(noirqtime, idle=poll, four vCPUs running on one pCPU). Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Radim <rkrcmar@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1470893795-3527-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/sched/cputime.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 1934f65..8b9bcc5 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -508,13 +508,20 @@ void account_process_tick(struct task_struct *p, int user_tick)
*/
void account_idle_ticks(unsigned long ticks)
{
-
+ cputime_t cputime, steal;
if (sched_clock_irqtime) {
irqtime_account_idle_ticks(ticks);
return;
}
- account_idle_time(jiffies_to_cputime(ticks));
+ cputime = cputime_one_jiffy;
+ steal = steal_account_process_time(cputime);
+
+ if (steal >= cputime)
+ return;
+
+ cputime -= steal;
+ account_idle_time(cputime);
}
/*