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 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
