[PATCH v5 0/7] Queued/runnable/running engine stats

[Tvrtko Ursulin <tursulin@ursulin.net>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Per-engine queue depths are an interesting metric for analyzing the system load
and also for users who wish to use it to load balance their submissions based
on it.

In this version I have split the metrics into three separate counters:

1. QUEUED - From execbuf time to request being runnable - runnable meaning until
            dependencies have been resolved and fences signaled.
2. RUNNABLE - From runnable to running on the GPU.
3. RUNNING - Running on the GPU.

When inspected with perf stat the output looks roughly like this:

#           time             counts unit events
   201.160490145               0.01      i915/rcs0-queued/
   201.160490145              19.13      i915/rcs0-runnable/
   201.160490145               2.39      i915/rcs0-running/

The reported numbers are average queue depths for the last query period.

v2:
 * Review feedback (see patch changelogs).
 * Renamed the counters and re-ordered some patches.

v3:
 * Review feedback and rebase.

v4:
 * Addition of last patch in the series, which supports a customer requirement
   to expose instantaneous queue values via the i915 query API.

v5:
 * Fixed accounting under wedging.
 * Error code ABI tweak.

Tvrtko Ursulin (7):
  drm/i915/pmu: Fix enable count array size and bounds checking
  drm/i915: Keep a count of requests waiting for a slot on GPU
  drm/i915: Keep a count of requests submitted from userspace
  drm/i915/pmu: Add queued counter
  drm/i915/pmu: Add runnable counter
  drm/i915/pmu: Add running counter
  drm/i915: Engine queues query

 drivers/gpu/drm/i915/i915_gem.c         |  1 +
 drivers/gpu/drm/i915/i915_pmu.c         | 81 +++++++++++++++++++++++++++++----
 drivers/gpu/drm/i915/i915_query.c       | 43 +++++++++++++++++
 drivers/gpu/drm/i915/i915_request.c     | 10 ++++
 drivers/gpu/drm/i915/intel_engine_cs.c  |  6 ++-
 drivers/gpu/drm/i915/intel_lrc.c        |  1 +
 drivers/gpu/drm/i915/intel_ringbuffer.h | 21 ++++++++-
 include/uapi/drm/i915_drm.h             | 45 +++++++++++++++++-
 8 files changed, 195 insertions(+), 13 deletions(-)

-- 
2.14.1

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