I am noticing the cpufreq_driver_lock is quite hot.
Currently on an idle 512 system perf shows me most of the system time is
spent on this lock.
- 84.18% [kernel] [k] _raw_spin_lock_irqsave
- _raw_spin_lock_irqsave
- 99.97% __cpufreq_cpu_get
cpufreq_cpu_get
__cpufreq_driver_getavg
dbs_check_cpu
od_dbs_timer
process_one_work
worker_thread
kthread
ret_from_fork
The data this lock protects is used in a read mostly situation.
While exprimenting I found turning the lock to a rwlock fixed the problem.
It seems like this might be amenable to using the RCU.
Any other ideas on how to properly resolve the issue?
Thanks,
Nate
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