Re: [Intel-gfx] [PATCH 20/51] drm/i915: Track 'serial' counts for virtual engines

From: Matthew Brost <matthew.brost@intel.com>
To: John Harrison <john.c.harrison@intel.com>
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 20/51] drm/i915: Track 'serial' counts for virtual engines
Date: Mon, 19 Jul 2021 18:54:00 -0700	[thread overview]
Message-ID: <20210720015400.GA13888@sdutt-i7> (raw)
In-Reply-To: <bb16d191-b605-9a93-0686-d6dacd722f1b@intel.com>

On Mon, Jul 19, 2021 at 06:28:47PM -0700, John Harrison wrote:
> On 7/16/2021 13:16, Matthew Brost wrote:
> > From: John Harrison <John.C.Harrison@Intel.com>
> > 
> > The serial number tracking of engines happens at the backend of
> > request submission and was expecting to only be given physical
> > engines. However, in GuC submission mode, the decomposition of virtual
> > to physical engines does not happen in i915. Instead, requests are
> > submitted to their virtual engine mask all the way through to the
> > hardware (i.e. to GuC). This would mean that the heart beat code
> > thinks the physical engines are idle due to the serial number not
> > incrementing.
> > 
> > This patch updates the tracking to decompose virtual engines into
> > their physical constituents and tracks the request against each. This
> > is not entirely accurate as the GuC will only be issuing the request
> > to one physical engine. However, it is the best that i915 can do given
> > that it has no knowledge of the GuC's scheduling decisions.
> > 
> > Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Still needs to pull in Tvrtko's updated subject and description.
> 

Forgot this in the post, already have it fixed locally.

Matt

> John.
> 
> > ---
> >   drivers/gpu/drm/i915/gt/intel_engine_types.h     |  2 ++
> >   .../gpu/drm/i915/gt/intel_execlists_submission.c |  6 ++++++
> >   drivers/gpu/drm/i915/gt/intel_ring_submission.c  |  6 ++++++
> >   drivers/gpu/drm/i915/gt/mock_engine.c            |  6 ++++++
> >   .../gpu/drm/i915/gt/uc/intel_guc_submission.c    | 16 ++++++++++++++++
> >   drivers/gpu/drm/i915/i915_request.c              |  4 +++-
> >   6 files changed, 39 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > index 1cb9c3b70b29..8ad304b2f2e4 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > @@ -388,6 +388,8 @@ struct intel_engine_cs {
> >   	void		(*park)(struct intel_engine_cs *engine);
> >   	void		(*unpark)(struct intel_engine_cs *engine);
> > +	void		(*bump_serial)(struct intel_engine_cs *engine);
> > +
> >   	void		(*set_default_submission)(struct intel_engine_cs *engine);
> >   	const struct intel_context_ops *cops;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > index 28492cdce706..920707e22eb0 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > @@ -3191,6 +3191,11 @@ static void execlists_release(struct intel_engine_cs *engine)
> >   	lrc_fini_wa_ctx(engine);
> >   }
> > +static void execlist_bump_serial(struct intel_engine_cs *engine)
> > +{
> > +	engine->serial++;
> > +}
> > +
> >   static void
> >   logical_ring_default_vfuncs(struct intel_engine_cs *engine)
> >   {
> > @@ -3200,6 +3205,7 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
> >   	engine->cops = &execlists_context_ops;
> >   	engine->request_alloc = execlists_request_alloc;
> > +	engine->bump_serial = execlist_bump_serial;
> >   	engine->reset.prepare = execlists_reset_prepare;
> >   	engine->reset.rewind = execlists_reset_rewind;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > index 5c4d204d07cc..61469c631057 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > @@ -1047,6 +1047,11 @@ static void setup_irq(struct intel_engine_cs *engine)
> >   	}
> >   }
> > +static void ring_bump_serial(struct intel_engine_cs *engine)
> > +{
> > +	engine->serial++;
> > +}
> > +
> >   static void setup_common(struct intel_engine_cs *engine)
> >   {
> >   	struct drm_i915_private *i915 = engine->i915;
> > @@ -1066,6 +1071,7 @@ static void setup_common(struct intel_engine_cs *engine)
> >   	engine->cops = &ring_context_ops;
> >   	engine->request_alloc = ring_request_alloc;
> > +	engine->bump_serial = ring_bump_serial;
> >   	/*
> >   	 * Using a global execution timeline; the previous final breadcrumb is
> > diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> > index 68970398e4ef..9203c766db80 100644
> > --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> > +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> > @@ -292,6 +292,11 @@ static void mock_engine_release(struct intel_engine_cs *engine)
> >   	intel_engine_fini_retire(engine);
> >   }
> > +static void mock_bump_serial(struct intel_engine_cs *engine)
> > +{
> > +	engine->serial++;
> > +}
> > +
> >   struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> >   				    const char *name,
> >   				    int id)
> > @@ -318,6 +323,7 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> >   	engine->base.cops = &mock_context_ops;
> >   	engine->base.request_alloc = mock_request_alloc;
> > +	engine->base.bump_serial = mock_bump_serial;
> >   	engine->base.emit_flush = mock_emit_flush;
> >   	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
> >   	engine->base.submit_request = mock_submit_request;
> > 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 7b3e1c91e689..372e0dc7617a 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -1485,6 +1485,20 @@ static void guc_release(struct intel_engine_cs *engine)
> >   	lrc_fini_wa_ctx(engine);
> >   }
> > +static void guc_bump_serial(struct intel_engine_cs *engine)
> > +{
> > +	engine->serial++;
> > +}
> > +
> > +static void virtual_guc_bump_serial(struct intel_engine_cs *engine)
> > +{
> > +	struct intel_engine_cs *e;
> > +	intel_engine_mask_t tmp, mask = engine->mask;
> > +
> > +	for_each_engine_masked(e, engine->gt, mask, tmp)
> > +		e->serial++;
> > +}
> > +
> >   static void guc_default_vfuncs(struct intel_engine_cs *engine)
> >   {
> >   	/* Default vfuncs which can be overridden by each engine. */
> > @@ -1493,6 +1507,7 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
> >   	engine->cops = &guc_context_ops;
> >   	engine->request_alloc = guc_request_alloc;
> > +	engine->bump_serial = guc_bump_serial;
> >   	engine->sched_engine->schedule = i915_schedule;
> > @@ -1828,6 +1843,7 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> >   	ve->base.cops = &virtual_guc_context_ops;
> >   	ve->base.request_alloc = guc_request_alloc;
> > +	ve->base.bump_serial = virtual_guc_bump_serial;
> >   	ve->base.submit_request = guc_submit_request;
> > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> > index 01aa3d1ee2b1..30ecdc46a12f 100644
> > --- a/drivers/gpu/drm/i915/i915_request.c
> > +++ b/drivers/gpu/drm/i915/i915_request.c
> > @@ -669,7 +669,9 @@ bool __i915_request_submit(struct i915_request *request)
> >   				     request->ring->vaddr + request->postfix);
> >   	trace_i915_request_execute(request);
> > -	engine->serial++;
> > +	if (engine->bump_serial)
> > +		engine->bump_serial(engine);
> > +
> >   	result = true;
> >   	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
> 
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