On 04/02/2019 15:01, Chris Wilson wrote:
Limit the NEWCLIENT boost to only give its small priority boost to fresh clients only that have no dependencies. The idea for using NEWCLIENT boosting, commit b16c765122f9 ("drm/i915: Priority boost for new clients"), is that short-lived streams are often interactive and require lower latency -- and that by executing those ahead of the long running hogs, the short-lived clients do little interfere with the system throughput by virtue of their short-lived nature. However, we were only considering the client's own timeline for determining whether or not it was a fresh stream. This allowed for compositors to wake up before their vblank and bump all of its client streams. However in testing with media-bench this results in chaining all cooperating contexts together preventing us from being able to reorder contexts to reduce bubbles (pipeline stalls), overall increasing latency, and reducing system throughput. The exact opposite of our intent. The compromise of applying the NEWCLIENT boost to strictly fresh clients (that do not wait upon anything else) should maintain the real-time response under load characteristics of FQ_CODEL, without locking together the long chains of dependencies across the system. References: b16c765122f9 ("drm/i915: Priority boost for new clients") Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_request.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index d14a1b225f47..04c65e6d83b9 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -980,7 +980,7 @@ void i915_request_add(struct i915_request *request) * Allow interactive/synchronous clients to jump ahead of * the bulk clients. (FQ_CODEL) */ - if (!prev || i915_request_completed(prev)) + if (list_empty(&request->sched.signalers_list)) attr.priority |= I915_PRIORITY_NEWCLIENT;engine->schedule(request, &attr);
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Regards, Tvrtko _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
