Re: [PATCH 04/19] sched: Prepare for Core-wide rq->lock

[Josh Don]

On Tue, Apr 27, 2021 at 10:10 AM Don Hiatt <dhiatt@xxxxxxxxxxxxxxxx> wrote:
> Hi Josh and Peter,
>
> I've been running into soft lookups and hard lockups when running a script
> that just cycles setting the cookie of a group of processes over and over again.
>
> Unfortunately the only way I can reproduce this is by setting the cookies
> on qemu. I've tried sysbench, stress-ng but those seem to work just fine.
>
> I'm running Peter's branch and even tried the suggested changes here but
> still see the same behavior. I enabled panic on hard lockup and here below
> is a snippet of the log.
>
> Is there anything you'd like me to try or have any debugging you'd like me to
> do? I'd certainly like to get to the bottom of this.

Hi Don,

I tried to repro using qemu, but did not generate a lockup. Could you
provide more details on what your script is doing (or better yet,
share the script directly)? I would have expected you to potentially
hit a lockup if you were cycling sched_core being enabled and
disabled, but it sounds like you are just recreating the cookie for a
process group over and over?

Best,
Josh