drm/i915: Add a tracepoint for using a semaphore
So that we can find the callers who introduce a ring stall. A single
ring stall is not too unwelcome, the right issue becomes when they start
to interlock and prevent any concurrent work. That, however, is a little
tricker to detect with a mere tracepoint!
v2: Rebrand it as a ring event, rather than an object event.
v3: Include the seqno in the tracepoint for posterity or something.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 1a0b74d..3ae925b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2625,6 +2625,7 @@
if (ret)
return ret;
+ trace_i915_gem_ring_sync_to(from, to, seqno);
ret = to->sync_to(to, from, seqno);
if (!ret)
/* We use last_read_seqno because sync_to()