From: Chris Wilson Date: Wed, 17 May 2017 12:10:05 +0000 (+0100) Subject: drm/i915/execlists: Reduce lock contention between schedule/submit_request X-Git-Tag: v4.13-rc1~45^2~32^2~40 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=349bdb68bd48f4e1861058ac2dbaa0aafd4ca38d;p=platform%2Fkernel%2Flinux-exynos.git drm/i915/execlists: Reduce lock contention between schedule/submit_request 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 Reviewed-by: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/20170517121007.27224-10-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 8529746..014b30a 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -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);