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@intel.com Signed-off-by: Matthew Brost matthew.brost@intel.com
.../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) {