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SubjectRe: [PATCH v4 0/2] cpufreq: cpufreq_driver_lock is hot on large systems
Date
On Friday, February 22, 2013 10:24:33 AM Nathan Zimmer wrote:
> I am noticing the cpufreq_driver_lock is quite hot.
> On an idle 512 system perf shows me most of the system time is spent on this
> lock. This is quite significant as top shows 5% of time in system time.
> My solution was to first convert the lock to a rwlock and then to the rcu.
>
> v2: Rebase
>
> v3: Read the RCU documentation instead of skimming it. Also I based on
> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git pm+acpi-3.9-rc1
> I assumed that was what you would prefer Rafael.
>
> v4: Removed an unnecessary syncronize_rcu().
>
>
> Nathan Zimmer (2):
> cpufreq: Convert the cpufreq_driver_lock to a rwlock
> cpufreq: Convert the cpufreq_driver_lock to use the rcu
>
> drivers/cpufreq/cpufreq.c | 286 ++++++++++++++++++++++++++++++++++------------
> 1 file changed, 211 insertions(+), 75 deletions(-)

I'm going to take patch [1/2] for v3.10, but patch [2/2] still needs some
work it seems. Is that correct? If so, are you going to send an update?

Rafael


--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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