Re: [PATCH 2/3] drm/xe/guc/ct: Increase wait timeout for g2h response

[John Harrison <john.c.harrison@intel.com>]

On 10/9/2024 03:56, Badal Nilawar wrote:
> Occasionally, the G2H worker starts running after a delay of more than
> a second even after being queued and activated by the Linux workqueue
> subsystem.
> To prevent G2H timeout errors, the wait timeout is being increased.
>
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/issues/1620
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/issues/2902
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: John Harrison <John.C.Harrison@Intel.com>
> ---
>   drivers/gpu/drm/xe/xe_guc_ct.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index b93b2821e4e8..dcc95c01b6f0 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -1019,7 +1019,7 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
>   		return ret;
>   	}
>   
> -	ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ);
> +	ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ * 3);
Is this change intended to be temporary until the fundamental scheduling 
issue with the workqueue is fixed? If so, there should be a TODO comment 
to that effect so that we remember to shrink the timeout back down again 
later. Three seconds seems like a long time to wait.

John.

>   
>   	/*
>   	 * It is possible that the g2h request may be cancelled while waiting for a response due