Messages in this thread | | | Date | Fri, 17 Jun 2016 06:16:51 -0700 | From | "Paul E. McKenney" <> | Subject | Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce cpufreq_update_util() overhead a bit") |
| |
On Fri, Jun 17, 2016 at 03:09:36PM +0200, Rafael J. Wysocki wrote: > On Fri, Jun 17, 2016 at 10:40 AM, Jisheng Zhang <jszhang@marvell.com> wrote: > > Dear all, > > > > On Fri, 17 Jun 2016 16:30:23 +0800 Jisheng Zhang wrote: > > > >> Dear all, > >> > >> I found one regression: In an idle system, wakeups/s (reported by powertop) > >> is increased a lot, e.g on a intel snb 4 core platform, the wakeup event > >> number is increased from 8 wakeups/s to 24 wakeup/s. bisect points to > >> this commit. I could send detailed bisect log if it's wanted. > >> > > > > more information maybe useful: after the commit, the top two wakeup source > > are > > > > Process [rcu_sched] > > > > Timer tick_sched_timer > > And what was there before the commit? > > Granted, I'm not seeing this on my systems. > > Paul, Peter, any ideas about what may be going on here?
Looks to me like this commit moved some code from synchronize_rcu() to synchronize_sched(). Assuming that this is a CONFIG_PREEMPT=y system, might there have been a decrease in the wakeups from the rcu_preempt kthread?
Thanx, Paul
| |