[Intel-gfx] [PATCH] drm/i915: fix exiting context timeout calculation

[Tvrtko Ursulin]

On 28/11/2022 16:52, Andrzej Hajda wrote:
> In case context is exiting preempt_timeout_ms is used for timeout,
> but since introduction of DRM_I915_PREEMPT_TIMEOUT_COMPUTE it increases
> to 7.5 seconds. Heartbeat occurs earlier but it is still 2.5s.
> 
> Fixes: d7a8680ec9fb21 ("drm/i915: Improve long running compute w/a for GuC submission")
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2410
> Signed-off-by: Andrzej Hajda <andrzej.hajda at intel.com>
> ---
> Hi all,
> 
> I am not sure what is expected solution here, and if my patch does not
> actually reverts intentions of patch d7a8680ec9fb21. Feel free to propose
> something better.
> Other alternative would be to increase t/o in IGT tests, but I am not sure
> if this is good direction.

Is it the hack with the FIXME marker from 47daf84a8bfb ("drm/i915: Make 
the heartbeat play nice with long pre-emption timeouts") that actually 
breaks things? (If IGT modifies the preempt timeout the heartbeat 
extension will not work as intended.)

If so, I think we agreed during review that was a weakness which needs 
to be addressed, but I would need to re-read the old threads to remember 
what was the plan. Regardless what it was it may be time is now to 
continue with those improvements.

Regards,

Tvrtko

> 
> Regards
> Andrzej
> ---
>   drivers/gpu/drm/i915/gt/intel_execlists_submission.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index 49a8f10d76c77b..bbbbcd9e00f947 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -1248,6 +1248,10 @@ static unsigned long active_preempt_timeout(struct intel_engine_cs *engine,
>   	/* Force a fast reset for terminated contexts (ignoring sysfs!) */
>   	if (unlikely(intel_context_is_banned(rq->context) || bad_request(rq)))
>   		return INTEL_CONTEXT_BANNED_PREEMPT_TIMEOUT_MS;
> +	else if (unlikely(intel_context_is_exiting(rq->context)))
> +		return min_t(typeof(unsigned long),
> +			     READ_ONCE(engine->props.preempt_timeout_ms),
> +			     CONFIG_DRM_I915_PREEMPT_TIMEOUT);
>   
>   	return READ_ONCE(engine->props.preempt_timeout_ms);
>   }