[Intel-gfx] [PATCH] drm/i915: Report request restarts for both execlists/guc

[Chris Wilson]

On Tue, Apr 25, 2017 at 01:21:47PM +0100, Tvrtko Ursulin wrote:
> 
> On 25/04/2017 11:38, Chris Wilson wrote:
> >As we now share the execlist_port[] tracking for both execlists/guc, we
> >can reset the inflight count on both and report which requests are being
> >restarted.
> >
> >Suggested-by: Michel Thierry <michel.thierry at intel.com>
> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >Cc: Michel Thierry <michel.thierry at intel.com>
> >Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> >Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >---
> > drivers/gpu/drm/i915/intel_lrc.c | 29 ++++++++++++++++-------------
> > 1 file changed, 16 insertions(+), 13 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> >index d3612969098f..961f4a2ad498 100644
> >--- a/drivers/gpu/drm/i915/intel_lrc.c
> >+++ b/drivers/gpu/drm/i915/intel_lrc.c
> >@@ -1147,14 +1147,11 @@ static int intel_init_workaround_bb(struct intel_engine_cs *engine)
> > 	return ret;
> > }
> >
> >-static u32 port_seqno(struct execlist_port *port)
> >-{
> >-	return port->request ? port->request->global_seqno : 0;
> >-}
> >-
> > static int gen8_init_common_ring(struct intel_engine_cs *engine)
> > {
> > 	struct drm_i915_private *dev_priv = engine->i915;
> >+	struct execlist_port *port = engine->execlist_port;
> >+	unsigned int n;
> > 	int ret;
> >
> > 	ret = intel_mocs_init_engine(engine);
> >@@ -1175,16 +1172,22 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
> >
> > 	/* After a GPU reset, we may have requests to replay */
> > 	clear_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted);
> >-	if (!i915.enable_guc_submission && !execlists_elsp_idle(engine)) {
> >-		DRM_DEBUG_DRIVER("Restarting %s from requests [0x%x, 0x%x]\n",
> >-				 engine->name,
> >-				 port_seqno(&engine->execlist_port[0]),
> >-				 port_seqno(&engine->execlist_port[1]));
> >-		engine->execlist_port[0].count = 0;
> >-		engine->execlist_port[1].count = 0;
> >-		execlists_submit_ports(engine);
> >+
> >+	for (n = 0; n < ARRAY_SIZE(engine->execlist_port); n++) {
> >+		if (!port[n].request)
> >+			break;
> 
> At some point we'll maybe want to start thinking about the
> for_each_port_request or something.

Something.

> >+
> >+		DRM_DEBUG_DRIVER("Restarting %s:%d from 0x%x\n",
> >+				 engine->name, n,
> >+				 port[n].request->global_seqno);
> >+
> >+		/* Discard the current inflight count */
> >+		port[n].count = 0;
> > 	}
> >
> >+	if (!i915.enable_guc_submission && !execlists_elsp_idle(engine))
> >+		execlists_submit_ports(engine);
> >+
> > 	return 0;
> > }
> >
> >
> 
> Looks okay to me. Someone has plans to start using counts in guc mode?

Spoilers. I moved the submission out of a few locks to reduce lock
contention (queued_spin_lock_slowpath exists for guc!), makes the CPU
numbers look better, but bxt/guc is still 3x higher latency. I just hope
it is broken firmware.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre