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

[Steven Rostedt]

On Thu, 24 Sep 2020 10:34:14 +0200
peterz@xxxxxxxxxxxxx wrote:

> 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.

I'd like to know the answer to Peter's question too. Why?

-- Steve