[PATCH v4 0/2] cpufreq: cpufreq_driver_lock is hot on large systems

[Nathan Zimmer]

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(-)

-- 
1.8.1.2

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