drm/i915/gt: Expose busywait duration to sysfs

Browse source

We busywait on an inflight request (one that is currently executing on
HW, and so might complete quickly) prior to setting up an interrupt and
sleeping. The trade off is that we keep an expensive CPU core busy in
order to avoid wake up latency: where that trade off should lie is best
left to the sysadmin.

The busywait mechanism can be compiled out with

	./scripts/config --set-val DRM_I915_SPIN_REQUEST 0

The maximum busywait duration can be adjusted per-engine using,

	/sys/class/drm/card?/engine/*/ms_busywait_duration_ns

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-4-chris@chris-wilson.co.uk

...

This commit is contained in:

Chris Wilson 2020-02-28 13:17:13 +00:00

parent 1a2695a746

commit 062444bbc6

5 changed files with 68 additions and 12 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

9

drivers/gpu/drm/i915/Kconfig.profile

View file

2

drivers/gpu/drm/i915/gt/intel_engine_cs.c

View file

1

drivers/gpu/drm/i915/gt/intel_engine_types.h

View file

49

drivers/gpu/drm/i915/gt/sysfs_engines.c

View file

19

drivers/gpu/drm/i915/i915_request.c

View file