Re: [PATCH] cpuidle: psd: add power sleep demotion prevention for fast I/O devices

[Bart Van Assche <bvanassche@acm.org>]

On 3/17/25 3:03 AM, King, Colin wrote:
> This code is optional, one can enable it or disable it via the config option. Also,
> even when it is built-in one can disable it by writing 0 to the sysfs file
>    /sys/devices/system/cpu/cpuidle/psd_cpu_lat_timeout_ms

I'm not sure we need even more configuration knobs in sysfs. How are
users expected to find this configuration option? How should they
decide whether to enable or to disable it?

Please take a look at this proposal and let me know whether this would
solve the issue that you are looking into: "[LSF/MM/BPF Topic] Energy-
Efficient I/O" (https://lore.kernel.org/linux-block/ad1018b6-7c0b-4d70-
b845-c869287d3cf3@acm.org/). The only disadvantage of this approach
compared to the cpuidle patch is that it requires RPM (runtime power
management) to be enabled. Maybe I should look into modifying the
approach such that it does not rely on RPM.

Thanks,

Bart.