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@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 1 +
drivers/gpu/drm/i915/i915_trace.h | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 82bc029..fa3b373 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2625,6 +2625,7 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
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()
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index daa6fdf..6e580c9 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -248,6 +248,32 @@ TRACE_EVENT(i915_gem_evict_vm,
TP_printk("dev=%d, vm=%p", __entry->vm->dev->primary->index, __entry->vm)
);
+TRACE_EVENT(i915_gem_ring_sync_to,
+ TP_PROTO(struct intel_ring_buffer *from,
+ struct intel_ring_buffer *to,
+ u32 seqno),
+ TP_ARGS(from, to, seqno),
+
+ TP_STRUCT__entry(
+ __field(u32, dev)
+ __field(u32, sync_from)
+ __field(u32, sync_to)
+ __field(u32, seqno)
+ ),
+
+ TP_fast_assign(
+ __entry->dev = from->dev->primary->index;
+ __entry->sync_from = from->id;
+ __entry->sync_to = to->id;
+ __entry->seqno = seqno;
+ ),
+
+ TP_printk("dev=%u, sync-from=%u, sync-to=%u, seqno=%u",
+ __entry->dev,
+ __entry->sync_from, __entry->sync_to,
+ __entry->seqno)
+);
+
TRACE_EVENT(i915_gem_ring_dispatch,
TP_PROTO(struct intel_ring_buffer *ring, u32 seqno, u32 flags),
TP_ARGS(ring, seqno, flags),
--
1.8.4.rc3
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