From patchwork Tue Apr 7 15:20:41 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 6172321 Return-Path: X-Original-To: patchwork-intel-gfx@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id EE9B9BF4A6 for ; Tue, 7 Apr 2015 15:22:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E735C203B1 for ; Tue, 7 Apr 2015 15:22:16 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 2116420397 for ; Tue, 7 Apr 2015 15:22:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3401A6E5AF; Tue, 7 Apr 2015 08:22:14 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from relay.fireflyinternet.com (hostedrelay.fireflyinternet.com [109.228.30.76]) by gabe.freedesktop.org (Postfix) with ESMTP id BC8D06E59E for ; Tue, 7 Apr 2015 08:22:10 -0700 (PDT) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by relay.fireflyinternet.com (FireflyRelay1) with ESMTP id 439610-1305619 for multiple; Tue, 07 Apr 2015 16:22:04 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 7 Apr 2015 16:20:41 +0100 Message-Id: <1428420094-18352-18-git-send-email-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1428420094-18352-1-git-send-email-chris@chris-wilson.co.uk> References: <1428420094-18352-1-git-send-email-chris@chris-wilson.co.uk> X-Authenticated-User: chris.alporthouse@surfanytime.net Cc: Daniel Vetter , Eero Tamminen , "Rantala, Valtteri" Subject: [Intel-gfx] [PATCH 17/70] drm/i915: Optimistically spin for the request completion X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This provides a nice boost to mesa in swap bound scenarios (as mesa throttles itself to the previous frame and given the scenario that will complete shortly). It will also provide a good boost to systems running with semaphores disabled and so frequently waiting on the GPU as it switches rings. In the most favourable of microbenchmarks, this can increase performance by around 15% - though in practice improvements will be marginal and rarely noticeable. v2: Account for user timeouts v3: Limit the spinning to a single jiffie (~1us) at most. On an otherwise idle system, there is no scheduler contention and so without a limit we would spin until the GPU is ready. v4: Drop forcewake - the lazy coherent access doesn't require it, and we have no reason to believe that the forcewake itself improves seqno coherency - it only adds delay. Signed-off-by: Chris Wilson Cc: Daniel Vetter Cc: Tvrtko Ursulin Cc: Eero Tamminen Cc: "Rantala, Valtteri" Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/i915_gem.c | 44 +++++++++++++++++++++++++++++++++++------ 1 file changed, 38 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index c7d9ee2f708a..47650327204e 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1181,6 +1181,29 @@ static bool missed_irq(struct drm_i915_private *dev_priv, return test_bit(ring->id, &dev_priv->gpu_error.missed_irq_rings); } +static int __i915_spin_request(struct drm_i915_gem_request *rq) +{ + unsigned long timeout; + + if (i915_gem_request_get_ring(rq)->irq_refcount) + return -EBUSY; + + timeout = jiffies + 1; + while (!need_resched()) { + if (i915_gem_request_completed(rq, true)) + return 0; + + if (time_after_eq(jiffies, timeout)) + break; + + cpu_relax_lowlatency(); + } + if (i915_gem_request_completed(rq, false)) + return 0; + + return -EAGAIN; +} + /** * __i915_wait_request - wait until execution of request has finished * @req: duh! @@ -1225,12 +1248,20 @@ int __i915_wait_request(struct drm_i915_gem_request *req, if (INTEL_INFO(dev)->gen >= 6) gen6_rps_boost(dev_priv, file_priv); - if (!irq_test_in_progress && WARN_ON(!ring->irq_get(ring))) - return -ENODEV; - /* Record current time in case interrupted by signal, or wedged */ trace_i915_gem_request_wait_begin(req); before = ktime_get_raw_ns(); + + /* Optimistic spin for the next jiffie before touching IRQs */ + ret = __i915_spin_request(req); + if (ret == 0) + goto out; + + if (!irq_test_in_progress && WARN_ON(!ring->irq_get(ring))) { + ret = -ENODEV; + goto out; + } + for (;;) { struct timer_list timer; @@ -1279,14 +1310,15 @@ int __i915_wait_request(struct drm_i915_gem_request *req, destroy_timer_on_stack(&timer); } } - now = ktime_get_raw_ns(); - trace_i915_gem_request_wait_end(req); - if (!irq_test_in_progress) ring->irq_put(ring); finish_wait(&ring->irq_queue, &wait); +out: + now = ktime_get_raw_ns(); + trace_i915_gem_request_wait_end(req); + if (timeout) { s64 tres = *timeout - (now - before);