drm/i915/execlists: Reduce lock contention between schedule/submit_request (349bdb68) · Commits · e / devices / android_kernel_teracube_emerald

If we do not require to perform priority bumping, and we haven't yet submitted the request, we can update its priority in situ and skip acquiring the engine locks -- thus avoiding any contention between us and submit/execute. v2: Remove the stack element from the list if we can do the early assignment. Signed-off-by:

Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by:

Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170517121007.27224-10-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -779,6 +779,19 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio)
		list_safe_reset_next(dep, p, dfs_link);
		}

		/* If we didn't need to bump any existing priorities, and we haven't
		* yet submitted this request (i.e. there is no potential race with
		* execlists_submit_request()), we can set our own priority and skip
		* acquiring the engine locks.
		*/
		if (request->priotree.priority == INT_MIN) {
		GEM_BUG_ON(!list_empty(&request->priotree.link));
		request->priotree.priority = prio;
		if (stack.dfs_link.next == stack.dfs_link.prev)
		return;
		__list_del_entry(&stack.dfs_link);
		}

		engine = request->engine;
		spin_lock_irq(&engine->timeline->lock);