From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Jisheng Zhang <jszhang@marvell.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce cpufreq_update_util() overhead a bit")
Date: Fri, 17 Jun 2016 16:03:53 +0200 [thread overview]
Message-ID: <20160617140353.GQ30154@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160617131651.GU3923@linux.vnet.ibm.com>
On Fri, Jun 17, 2016 at 06:16:51AM -0700, Paul E. McKenney wrote:
> > 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?
The 'funny' thing is though; those synchronize thingies are only reached
when we change cpufreq policy, so things like:
for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i ; done
Something which is hardly possible when idle. Weird.
next prev parent reply other threads:[~2016-06-17 14:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-17 8:30 Jisheng Zhang
2016-06-17 8:40 ` Jisheng Zhang
2016-06-17 13:09 ` Rafael J. Wysocki
2016-06-17 13:16 ` Paul E. McKenney
2016-06-17 14:03 ` Peter Zijlstra [this message]
2016-06-17 15:32 ` regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early") Jisheng Zhang
2016-06-17 15:40 ` Rafael J. Wysocki
2016-06-17 15:42 ` Rafael J. Wysocki
2016-06-17 15:53 ` Jisheng Zhang
2016-06-17 16:09 ` Jisheng Zhang
2016-06-25 0:14 ` Rafael J. Wysocki
2016-06-25 15:09 ` Pandruvada, Srinivas
2016-06-26 0:27 ` Doug Smythies
2016-06-27 6:08 ` Jisheng Zhang
2016-06-23 16:07 ` Doug Smythies
2016-06-25 0:03 ` Rafael J. Wysocki
2016-06-17 15:32 ` regression caused by 08f511fd41c3 ("cpufreq: Reduce cpufreq_update_util() overhead a bit") Rafael J. Wysocki
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