[RFC,00/12] Per client engine busyness

Message

Tvrtko Ursulin March 11, 2020, 6:26 p.m. UTC

From: Tvrtko Ursulin <[e-mail]>

Another re-spin of the per-client engine busyness series. Highlights from this
version:

 * Last two patches contain a hybrid method of tracking context runtime. PPHWSP
   tracked one is used as a baseline and then on top i915 tracks the start time
   of when context was last started executing on the GPU. Together this should
   give better overall resilience against spammy workloads and also provides
   visibility to long/infinite batches.

Internally we track time spent on engines for each struct intel_context. This
can serve as a building block for several features from the want list:
smarter scheduler decisions, getrusage(2)-like per-GEM-context functionality
wanted by some customers, cgroups controller, dynamic SSEU tuning,...

Externally, in sysfs, we expose time spent on GPU per client and per engine
class.

Sysfs interface enables us to implement a "top-like" tool for GPU tasks. Or with
a "screenshot":
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
intel-gpu-top -  906/ 955 MHz;    0% RC6;  5.30 Watts;      933 irqs/s

      IMC reads:     4414 MiB/s
     IMC writes:     3805 MiB/s

          ENGINE      BUSY                                      MI_SEMA MI_WAIT
     Render/3D/0   93.46% |████████████████████████████████▋  |      0%      0%
       Blitter/0    0.00% |                                   |      0%      0%
         Video/0    0.00% |                                   |      0%      0%
  VideoEnhance/0    0.00% |                                   |      0%      0%

  PID            NAME  Render/3D      Blitter        Video      VideoEnhance
 2733       neverball |██████▌     ||            ||            ||            |
 2047            Xorg |███▊        ||            ||            ||            |
 2737        glxgears |█▍          ||            ||            ||            |
 2128           xfwm4 |            ||            ||            ||            |
 2047            Xorg |            ||            ||            ||            |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Implementation wise we add a a bunch of files in sysfs like:

	# cd /sys/class/drm/card0/clients/
	# tree
	.
	├── 7
	│   ├── busy
	│   │   ├── 0
	│   │   ├── 1
	│   │   ├── 2
	│   │   └── 3
	│   ├── name
	│   └── pid
	├── 8
	│   ├── busy
	│   │   ├── 0
	│   │   ├── 1
	│   │   ├── 2
	│   │   └── 3
	│   ├── name
	│   └── pid
	└── 9
	    ├── busy
	    │   ├── 0
	    │   ├── 1
	    │   ├── 2
	    │   └── 3
	    ├── name
	    └── pid

Files in 'busy' directories are numbered using the engine class ABI values and
they contain accumulated nanoseconds each client spent on engines of a
respective class.

It is stil a RFC since it misses dedicated test cases to ensure things really
work as advertised.

Tvrtko Ursulin (10):
  drm/i915: Expose list of clients in sysfs
  drm/i915: Update client name on context create
  drm/i915: Make GEM contexts track DRM clients
  drm/i915: Use explicit flag to mark unreachable intel_context
  drm/i915: Track runtime spent in unreachable intel_contexts
  drm/i915: Track runtime spent in closed GEM contexts
  drm/i915: Track all user contexts per client
  drm/i915: Expose per-engine client busyness
  drm/i915: Track context current active time
  drm/i915: Prefer software tracked context busyness

 drivers/gpu/drm/i915/Makefile                 |   3 +-
 drivers/gpu/drm/i915/gem/i915_gem_context.c   |  66 ++-
 .../gpu/drm/i915/gem/i915_gem_context_types.h |  21 +-
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |   2 +-
 drivers/gpu/drm/i915/gt/intel_context.c       |  18 +-
 drivers/gpu/drm/i915/gt/intel_context.h       |   6 +-
 drivers/gpu/drm/i915/gt/intel_context_types.h |  25 +-
 drivers/gpu/drm/i915/gt/intel_lrc.c           |  55 ++-
 drivers/gpu/drm/i915/gt/selftest_lrc.c        |  10 +-
 drivers/gpu/drm/i915/i915_debugfs.c           |  31 +-
 drivers/gpu/drm/i915/i915_drm_client.c        | 434 ++++++++++++++++++
 drivers/gpu/drm/i915/i915_drm_client.h        |  94 ++++
 drivers/gpu/drm/i915/i915_drv.h               |   5 +
 drivers/gpu/drm/i915/i915_gem.c               |  35 +-
 drivers/gpu/drm/i915/i915_gpu_error.c         |  25 +-
 drivers/gpu/drm/i915/i915_sysfs.c             |   8 +
 16 files changed, 756 insertions(+), 82 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/i915_drm_client.c
 create mode 100644 drivers/gpu/drm/i915/i915_drm_client.h