On 10/25/2021 09:34, Matthew Brost wrote:

Hide the guc_id and tail fields, for request trace points, behind CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS Kconfig option. Trace points are ABI (maybe?) so don't change them without kernel developers Kconfig options.

The i915 sw arch team have previously hard blocked requests for changes to trace points from user land tool developers on the grounds that trace points are not ABI and are free to change at whim as and when the i915 internal implementation changes. They are purely for use of developers to debug the i915 driver as the i915 driver currently stands at any given instant.

So I don't see how it can be argued that we must not update any trace points to allow for debugging of i915 scheduling issues on current platforms. And having to enable extra config options just to keep existing higher level trace points usable seems broken.

John.

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

drivers/gpu/drm/i915/i915_trace.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index 9795f456cccf..4f5238d02b51 100644 --- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -787,6 +787,7 @@ TRACE_EVENT(i915_request_queue, __entry->ctx, __entry->seqno, __entry->flags) );

+#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS) DECLARE_EVENT_CLASS(i915_request, TP_PROTO(struct i915_request *rq), TP_ARGS(rq), @@ -816,6 +817,32 @@ DECLARE_EVENT_CLASS(i915_request, __entry->guc_id, __entry->ctx, __entry->seqno, __entry->tail) ); +#else +DECLARE_EVENT_CLASS(i915_request,

•    TP_PROTO(struct i915_request *rq),
  

•    TP_ARGS(rq),
  

•    TP_STRUCT__entry(
  

• 	     __field(u32, dev)
  

• 	     __field(u64, ctx)
  

• 	     __field(u16, class)
  

• 	     __field(u16, instance)
  

• 	     __field(u32, seqno)
  

• 	     ),
  

•    TP_fast_assign(
  

• 	   __entry->dev = rq->engine->i915->drm.primary->index;
  

• 	   __entry->class = rq->engine->uabi_class;
  

• 	   __entry->instance = rq->engine->uabi_instance;
  

• 	   __entry->ctx = rq->fence.context;
  

• 	   __entry->seqno = rq->fence.seqno;
  

• 	   ),
  

•    TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u",
  

•       __entry->dev, __entry->class, __entry->instance,
  

•       __entry->ctx, __entry->seqno)
  

+); +#endif

DEFINE_EVENT(i915_request, i915_request_add, TP_PROTO(struct i915_request *rq),

Quoting Matthew Brost (2021-10-25 19:34:04)

Hide the guc_id and tail fields, for request trace points, behind CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS Kconfig option. Trace points are ABI (maybe?) so don't change them without kernel developers Kconfig options.

I've pushed the simple fix to eliminate the 'guc_id' field.

In my opinion a separate tracepoint with more information would be a better choice here compared to mutating an existing one.

The idea with LOW_LEVEL_TRACEPOINTS is to make sure there are two sets of tracepoints: one that is quasi stable and the other that is unstable. Mutating the other set when the unstable set is enabled kind of breaks that clean split.

Regards, Joonas

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

drivers/gpu/drm/i915/i915_trace.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index 9795f456cccf..4f5238d02b51 100644 --- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -787,6 +787,7 @@ TRACE_EVENT(i915_request_queue, __entry->ctx, __entry->seqno, __entry->flags) );

+#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS) DECLARE_EVENT_CLASS(i915_request, TP_PROTO(struct i915_request *rq), TP_ARGS(rq), @@ -816,6 +817,32 @@ DECLARE_EVENT_CLASS(i915_request, __entry->guc_id, __entry->ctx, __entry->seqno, __entry->tail) ); +#else +DECLARE_EVENT_CLASS(i915_request,

•       TP_PROTO(struct i915_request *rq),
  

•       TP_ARGS(rq),
  

•       TP_STRUCT__entry(
  

•                        __field(u32, dev)
  

•                        __field(u64, ctx)
  

•                        __field(u16, class)
  

•                        __field(u16, instance)
  

•                        __field(u32, seqno)
  

•                        ),
  

•       TP_fast_assign(
  

•                      __entry->dev = rq->engine->i915->drm.primary->index;
  

•                      __entry->class = rq->engine->uabi_class;
  

•                      __entry->instance = rq->engine->uabi_instance;
  

•                      __entry->ctx = rq->fence.context;
  

•                      __entry->seqno = rq->fence.seqno;
  

•                      ),
  

•       TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u",
  

•                 __entry->dev, __entry->class, __entry->instance,
  

•                 __entry->ctx, __entry->seqno)
  

+); +#endif

DEFINE_EVENT(i915_request, i915_request_add, TP_PROTO(struct i915_request *rq), -- 2.32.0