Messages in this thread |  | | | Subject | Dynamic configure max_cstate | | From | "Zhang, Yanmin" <> | | Date | Mon, 27 Jul 2009 13:30:13 +0800 |
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When running a fio workload, I found sometimes cpu C state has big impact on the result. Mostly, fio is a disk I/O workload which doesn't spend much time with cpu, so cpu switch to C2/C3 freqently and the latency is big.
If I start kernel with idle=poll or processor.max_cstate=1, the result is quite good. Consider a scenario that machine is busy at daytime and free at night. Could we add a dynamic configuration interface for processor.max_cstate or something similiar with sysfs? So user applications could change the max_cstate dynamically? For example, we could add a new parameter to function cpuidle_governor->select to mark the highest c state.
Any idea?
Yanmin
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