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

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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@xxxxxxxxx>
fine for me:

Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>

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






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