From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D206C433DF for ; Wed, 8 Jul 2020 22:17:45 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 52A0620708 for ; Wed, 8 Jul 2020 22:17:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 52A0620708 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 96B946E941; Wed, 8 Jul 2020 22:17:44 +0000 (UTC) Received: from fireflyinternet.com (unknown [77.68.26.236]) by gabe.freedesktop.org (Postfix) with ESMTPS id 828CF6E941 for ; Wed, 8 Jul 2020 22:17:43 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from build.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 21758516-1500050 for multiple; Wed, 08 Jul 2020 23:17:31 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Wed, 8 Jul 2020 23:17:29 +0100 Message-Id: <20200708221729.17113-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915: Soften the tasklet flush frequency before waits X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Chris Wilson Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" We include a tasklet flush before waiting on a request as a precaution against the HW being lax in event signaling. We now have a precautionary flush in the engine's heartbeat and so do not need to be quite so zealous on every request wait. If we focus on the request, the only tasklet flush that matters is if there is a delay in submitting this request to HW, so if the request is not ready to be executed no advantage in reducing this wait can be gained by running the tasklet. And there is little point in doing busy work for no result. Signed-off-by: Chris Wilson Cc: Mika Kuoppala --- drivers/gpu/drm/i915/i915_request.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 3bb7320249ae..19adb7b82a2e 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1790,6 +1790,24 @@ long i915_request_wait(struct i915_request *rq, if (dma_fence_add_callback(&rq->fence, &wait.cb, request_wait_wake)) goto out; + /* + * Flush the submission tasklet, but only if it may help this request. + * + * We sometimes experience some latency between the HW interrupts and + * tasklet execution (mostly due to ksoftirqd latency, but it can also + * be due to lazy CS events), so lets run the tasklet manually if there + * is a chance it may submit this request. If the request is not ready + * to run, as it is waiting for other fences to be signaled, flushing + * the tasklet is busy work without any advantage for this client. + * + * If the HW is being lazy, this is the last chance before we go to + * sleep to catch any pending events. We will check periodically in + * the heartbeat to flush the submission tasklets as a last resort + * for unhappy HW. + */ + if (i915_request_is_ready(rq)) + intel_engine_flush_submission(rq->engine); + for (;;) { set_current_state(state); @@ -1798,8 +1816,6 @@ long i915_request_wait(struct i915_request *rq, break; } - intel_engine_flush_submission(rq->engine); - if (signal_pending_state(state, current)) { timeout = -ERESTARTSYS; break; -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx