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 split the lock into two parts, cpu_driver_lock and
cpu_data_lock, with the cpufreq_driver also being protected by the RCU.
There was measurable heat left on the cpufreq_data_lock in __cpufreq_cpu_get.
So in the second part I converted the cpufreq_data_lock to be a rw lock since
an rcu solution was not apparent, at least to me.
v5: Go a different way and split up the lock and use the rcu
v6: use bools instead of checking function pointers
covert the cpufreq_data_lock to a rwlock
Nathan Zimmer (2):
cpufreq: split the cpufreq_driver_lock and use the rcu
cpufreq: covert the cpufreq_data_lock to a spinlock
drivers/cpufreq/cpufreq.c | 302 +++++++++++++++++++++++++++++++++-------------
1 file changed, 219 insertions(+), 83 deletions(-)
--
1.8.1.2
--
To unsubscribe from this list: send the line "unsubscribe cpufreq" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
