Re: [PATCH 0/2] measure latency of cpu hotplug path

From: peterz
Date: Thu Sep 24 2020 - 04:34:31 EST


On Wed, Sep 23, 2020 at 04:37:44PM -0700, Prasad Sodagudi wrote:
> There are all changes related to cpu hotplug path and would like to seek
> upstream review. These are all patches in Qualcomm downstream kernel
> for a quite long time. First patch sets the rt prioity to hotplug
> task and second patch adds cpuhp trace events.
>
> 1) cpu-hotplug: Always use real time scheduling when hotplugging a CPU
> 2) cpu/hotplug: Add cpuhp_latency trace event

Why? Hotplug is a known super slow path. If you care about hotplug
latency you're doing it wrong.