On 24/06/2021 08:04, Matthew Brost wrote:
Add trace points for request dependencies and GuC submit. Extended
existing request trace points to include submit fence value,, guc_id,
and ring tail value.
Cc: John Harrison <john.c.harrison@xxxxxxxxx>
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 3 ++
drivers/gpu/drm/i915/i915_request.c | 3 ++
drivers/gpu/drm/i915/i915_trace.h | 39 ++++++++++++++++++-
3 files changed, 43 insertions(+), 2 deletions(-)
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 89b3c7e5d15b..c2327eebc09c 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -422,6 +422,7 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
guc->stalled_request = last;
return false;
}
+ trace_i915_request_guc_submit(last);
}
guc->stalled_request = NULL;
@@ -642,6 +643,8 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
ret = guc_add_request(guc, rq);
if (ret == -EBUSY)
guc->stalled_request = rq;
+ else
+ trace_i915_request_guc_submit(rq);
return ret;
}
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index d92c9f25c9f4..7f7aa096e873 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1344,6 +1344,9 @@ __i915_request_await_execution(struct i915_request *to,
return err;
}
+ trace_i915_request_dep_to(to);
+ trace_i915_request_dep_from(from);
Are those two guaranteed to be atomic ie. no other dep_to/dep_from can
get injected in the middle of them and if so what guarantees that?
Actually we had an internal discussion going in November 2019 on these
very tracepoints which I think was left hanging in the air.
There I was suggesting you create a single tracepoint in the format of
"from -> to", so it's clear without any doubt what is going on.
I also suggested this should out outside the GuC patch since it is
backend agnostic.
I also asked why only this flavour of dependencies and not all. You said
this was the handy one for debugging GuC backend issues. I said in that
case you should name it trace_i915_request_await_request so it is
clearer it does not cover all dependencies.
As it stands it is a bit misleadingly named, has that question mark
around atomicity, and also is not GuC specific. So really I wouldn't
think it passes the bar in the current state.
Regards,
Tvrtko
P.S. Same discussion from 2019 also talked about
trace_i915_request_guc_submit and how it exactly aligns to existing
request in tracepoint. You were saying the new one is handy because it
corresponds with H2G, as the last request_in of the group would trigger
it. I was saying that then you could either know implicitly last
request_in triggers H2G, or that you could consider adding explicit H2G
tracepoints.
+
/* Couple the dependency tree for PI on this exposed to->fence */
if (to->engine->sched_engine->schedule) {
err = i915_sched_node_add_dependency(&to->sched,
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 6778ad2a14a4..b02d04b6c8f6 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -794,22 +794,27 @@ DECLARE_EVENT_CLASS(i915_request,
TP_STRUCT__entry(
__field(u32, dev)
__field(u64, ctx)
+ __field(u32, guc_id)
__field(u16, class)
__field(u16, instance)
__field(u32, seqno)
+ __field(u32, tail)
),
TP_fast_assign(
__entry->dev = rq->engine->i915->drm.primary->index;
__entry->class = rq->engine->uabi_class;
__entry->instance = rq->engine->uabi_instance;
+ __entry->guc_id = rq->context->guc_id;
__entry->ctx = rq->fence.context;
__entry->seqno = rq->fence.seqno;
+ __entry->tail = rq->tail;
),
- TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u",
+ TP_printk("dev=%u, engine=%u:%u, guc_id=%u, ctx=%llu, seqno=%u, tail=%u",
__entry->dev, __entry->class, __entry->instance,
- __entry->ctx, __entry->seqno)
+ __entry->guc_id, __entry->ctx, __entry->seqno,
+ __entry->tail)
);
DEFINE_EVENT(i915_request, i915_request_add,
@@ -818,6 +823,21 @@ DEFINE_EVENT(i915_request, i915_request_add,
);
#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS)
+DEFINE_EVENT(i915_request, i915_request_dep_to,
+ TP_PROTO(struct i915_request *rq),
+ TP_ARGS(rq)
+);
+
+DEFINE_EVENT(i915_request, i915_request_dep_from,
+ TP_PROTO(struct i915_request *rq),
+ TP_ARGS(rq)
+);
+
+DEFINE_EVENT(i915_request, i915_request_guc_submit,
+ TP_PROTO(struct i915_request *rq),
+ TP_ARGS(rq)
+);
+
DEFINE_EVENT(i915_request, i915_request_submit,
TP_PROTO(struct i915_request *rq),
TP_ARGS(rq)
@@ -887,6 +907,21 @@ TRACE_EVENT(i915_request_out,
#else
#if !defined(TRACE_HEADER_MULTI_READ)
+static inline void
+trace_i915_request_dep_to(struct i915_request *rq)
+{
+}
+
+static inline void
+trace_i915_request_dep_from(struct i915_request *rq)
+{
+}
+
+static inline void
+trace_i915_request_guc_submit(struct i915_request *rq)
+{
+}
+
static inline void
trace_i915_request_submit(struct i915_request *rq)
{
