$ nice ffmmpeg ...transcode my videos...
$ my-favourite-game
And have the nice hint apply to GPU parts of the transcode pipeline as well?
This would in fact follow the approach taken by kernel's block scheduler where
ionice is by default inherited from process nice.
This series implements the same idea by inheriting context creator and batch
buffer submitted nice value as context nice. To avoid influencing GPU scheduling
aware clients this is done only one for contexts where userspace hasn't
explicitly specified a non-default scheduling priority
With the series applied I simulated the scenario of a background GPU task
running simultaneously with an interactive client, varying the hog's nice value.
These were the results:
GPU hog (nice) | TRex fps | perf drop
---------------+---------------+------------
no hog | 48.9 | - n/a -
0 | 42.7 | -13%
10 | 47.9 | -2%
-10 | 29.0 | -41%
As can be seen running the background GPU task re-niced can restore the
performance of the foreground task to almost the level when it is running alone
on the machine.
The approach is completely compatible with GuC and drm/scheduler since all
support at least low/normal/high priority levels with just the granularity of
available control differing. In other words with GuC scheduling there is no
difference between nice 5 and 10, both would map to low priority, but the
default case of positive or negative nice, versus nice 0, is still correctly
propagated to the firmware scheduler.
v2:
* Moved notifier outside task_rq_lock.
* Some improvements and restructuring on the i915 side of the series.
v3:
* Dropped task nice notifier - inheriting nice on request submit time is good
enough.
Tvrtko Ursulin (3):
drm/i915: Make some recently added vfuncs use full scheduling
attribute
drm/i915: Inherit process nice for context scheduling priority
drm/i915: Inherit submitter nice when scheduling requests
drivers/gpu/drm/i915/gem/i915_gem_context.c | 6 +++++-
.../gpu/drm/i915/gt/intel_execlists_submission.c | 6 ++++--
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 3 ++-
drivers/gpu/drm/i915/i915_request.c | 7 +++++--
drivers/gpu/drm/i915/i915_request.h | 5 +++++
drivers/gpu/drm/i915/i915_scheduler.c | 16 ++++++++++------
drivers/gpu/drm/i915/i915_scheduler.h | 14 ++++++++++++++
drivers/gpu/drm/i915/i915_scheduler_types.h | 12 ++++++++++--
8 files changed, 55 insertions(+), 14 deletions(-)
--
2.32.0
