Re: [Intel-gfx] [PATCH] drm/i915/guc: do not capture error state on exiting context

[Andrzej Hajda <andrzej.hajda@intel.com>]

On 27.09.2022 09:45, Tvrtko Ursulin wrote:
>
> On 27/09/2022 07:49, Andrzej Hajda wrote:
>>
>>
>> On 27.09.2022 01:34, Ceraolo Spurio, Daniele wrote:
>>>
>>>
>>> On 9/26/2022 3:44 PM, Andi Shyti wrote:
>>>> Hi Andrzej,
>>>>
>>>> On Mon, Sep 26, 2022 at 11:54:09PM +0200, Andrzej Hajda wrote:
>>>>> Capturing error state is time consuming (up to 350ms on DG2), so 
>>>>> it should
>>>>> be avoided if possible. Context reset triggered by context removal 
>>>>> is a
>>>>> good example.
>>>>> With this patch multiple igt tests will not timeout and should run 
>>>>> faster.
>>>>>
>>>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1551
>>>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3952
>>>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5891
>>>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6268
>>>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6281
>>>>> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
>>>> fine for me:
>>>>
>>>> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
>>>>
>>>> Just to be on the safe side, can we also have the ack from any of
>>>> the GuC folks? Daniele, John?
>>>>
>>>> Andi
>>>>
>>>>
>>>>> ---
>>>>>   drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 3 ++-
>>>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c 
>>>>> b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>>>> index 22ba66e48a9b01..cb58029208afe1 100644
>>>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>>>> @@ -4425,7 +4425,8 @@ static void guc_handle_context_reset(struct 
>>>>> intel_guc *guc,
>>>>>       trace_intel_context_reset(ce);
>>>>>         if (likely(!intel_context_is_banned(ce))) {
>>>>> -        capture_error_state(guc, ce);
>>>>> +        if (!intel_context_is_exiting(ce))
>>>>> +            capture_error_state(guc, ce);
>
> I am not sure here - if we have a persistent context which caused a 
> GPU hang I'd expect we'd still want error capture.
>
> What causes the reset in the affected IGTs? Always preemption timeout?

Affected tests performs always context destroy with bb having 
IGT_SPIN_NO_PREEMPTION, and "preempt_timeout_ms" set to 50.
So I guess yes.

Regards
Andrzej


>
>>>>>           guc_context_replay(ce);
>>>
>>> You definitely don't want to replay requests of a context that is 
>>> going away.
>>
>> My intention was to just avoid error capture, but that's even better, 
>> only condition change:
>> -        if (likely(!intel_context_is_banned(ce))) {
>> +       if (likely(intel_context_is_schedulable(ce)))  {
>
> Yes that helper was intended to be used for contexts which should not 
> be scheduled post exit or ban.
>
> Daniele - you say there are some misses in the GuC backend. Should 
> most, or even all in intel_guc_submission.c be converted to use 
> intel_context_is_schedulable? My idea indeed was that "ban" should be 
> a level up from the backends. Backend should only distinguish between 
> "should I run this or not", and not the reason.
>
> Regards,
>
> Tvrtko
>
>>
>>>
>>> This seems at least in part due to 
>>> https://patchwork.freedesktop.org/patch/487531/, where we replaced 
>>> the "context_ban" with "context_exiting". There are several places 
>>> where we skipped operations if the context was banned (here 
>>> included) which are now not covered anymore for exiting contexts. 
>>> Maybe we need a new checker function to check both flags in places 
>>> where we don't care why the context is being removed (ban vs 
>>> exiting), just that it is?
>>>
>>> Daniele
>>>
>>>>>       } else {
>>>>>           drm_info(&guc_to_gt(guc)->i915->drm,
>>
>> And maybe degrade above to drm_dbg, to avoid spamming dmesg?
>>
>> Regards
>> Andrzej
>>
>>
>>>>> -- 
>>>>> 2.34.1
>>>
>>