From d7a8680ec9fb217987a9569aba1abeed886805f0 Mon Sep 17 00:00:00 2001 From: John Harrison Date: Thu, 6 Oct 2022 14:38:13 -0700 Subject: drm/i915: Improve long running compute w/a for GuC submission A workaround was added to the driver to allow compute workloads to run 'forever' by disabling pre-emption on the RCS engine for Gen12. It is not totally unbound as the heartbeat will kick in eventually and cause a reset of the hung engine. However, this does not work well in GuC submission mode. In GuC mode, the pre-emption timeout is how GuC detects hung contexts and triggers a per engine reset. Thus, disabling the timeout means also losing all per engine reset ability. A full GT reset will still occur when the heartbeat finally expires, but that is a much more destructive and undesirable mechanism. The purpose of the workaround is actually to give compute tasks longer to reach a pre-emption point after a pre-emption request has been issued. This is necessary because Gen12 does not support mid-thread pre-emption and compute tasks can have long running threads. So, rather than disabling the timeout completely, just set it to a 'long' value. v2: Review feedback from Tvrtko - must hard code the 'long' value instead of determining it algorithmically. So make it an extra CONFIG definition. Also, remove the execlist centric comment from the existing pre-emption timeout CONFIG option given that it applies to more than just execlists. Signed-off-by: John Harrison Reviewed-by: Daniele Ceraolo Spurio Acked-by: Michal Mrozek Acked-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20221006213813.1563435-5-John.C.Harrison@Intel.com --- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/i915/gt/intel_engine_cs.c') diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 7c5b33ccedd0..3b7d750ad054 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -508,9 +508,14 @@ static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id, engine->props.timeslice_duration_ms = CONFIG_DRM_I915_TIMESLICE_DURATION; - /* Override to uninterruptible for OpenCL workloads. */ + /* + * Mid-thread pre-emption is not available in Gen12. Unfortunately, + * some compute workloads run quite long threads. That means they get + * reset due to not pre-empting in a timely manner. So, bump the + * pre-emption timeout value to be much higher for compute engines. + */ if (GRAPHICS_VER(i915) == 12 && (engine->flags & I915_ENGINE_HAS_RCS_REG_STATE)) - engine->props.preempt_timeout_ms = 0; + engine->props.preempt_timeout_ms = CONFIG_DRM_I915_PREEMPT_TIMEOUT_COMPUTE; /* Cap properties according to any system limits */ #define CLAMP_PROP(field) \ -- cgit