From patchwork Sat Jul 28 16:46:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10548025 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AAE4B14E0 for ; Sat, 28 Jul 2018 16:46:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9A1172B104 for ; Sat, 28 Jul 2018 16:46:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8C88B2B107; Sat, 28 Jul 2018 16:46:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 35DA62B104 for ; Sat, 28 Jul 2018 16:46:49 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 38BC76E21C; Sat, 28 Jul 2018 16:46:47 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0B94C6E218 for ; Sat, 28 Jul 2018 16:46:43 +0000 (UTC) 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 fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 12491854-1500050 for multiple; Sat, 28 Jul 2018 17:46:21 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Sat, 28 Jul 2018 17:46:21 +0100 Message-Id: <20180728164623.10613-3-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180728164623.10613-1-chris@chris-wilson.co.uk> References: <20180728164623.10613-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 3/5] drm/i915: Increase busyspin limit before a context-switch X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ben Widawsky , Eero Tamminen Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Looking at the distribution of i915_wait_request for a set of GL benchmarks, we see: broadwell# python bcc/tools/funclatency.py -u i915_wait_request usecs : count distribution 0 -> 1 : 29184 |****************************************| 2 -> 3 : 5767 |******* | 4 -> 7 : 3000 |**** | 8 -> 15 : 491 | | 16 -> 31 : 140 | | 32 -> 63 : 203 | | 64 -> 127 : 543 | | 128 -> 255 : 881 |* | 256 -> 511 : 1209 |* | 512 -> 1023 : 1739 |** | 1024 -> 2047 : 22855 |******************************* | 2048 -> 4095 : 1725 |** | 4096 -> 8191 : 5813 |******* | 8192 -> 16383 : 5348 |******* | 16384 -> 32767 : 1000 |* | 32768 -> 65535 : 4400 |****** | 65536 -> 131071 : 296 | | 131072 -> 262143 : 225 | | 262144 -> 524287 : 4 | | 524288 -> 1048575 : 1 | | 1048576 -> 2097151 : 1 | | 2097152 -> 4194303 : 1 | | broxton# python bcc/tools/funclatency.py -u i915_wait_request usecs : count distribution 0 -> 1 : 5523 |************************************* | 2 -> 3 : 1340 |********* | 4 -> 7 : 2100 |************** | 8 -> 15 : 755 |***** | 16 -> 31 : 211 |* | 32 -> 63 : 53 | | 64 -> 127 : 71 | | 128 -> 255 : 113 | | 256 -> 511 : 262 |* | 512 -> 1023 : 358 |** | 1024 -> 2047 : 1105 |******* | 2048 -> 4095 : 848 |***** | 4096 -> 8191 : 1295 |******** | 8192 -> 16383 : 5894 |****************************************| 16384 -> 32767 : 4270 |**************************** | 32768 -> 65535 : 5622 |************************************** | 65536 -> 131071 : 306 |** | 131072 -> 262143 : 50 | | 262144 -> 524287 : 76 | | 524288 -> 1048575 : 34 | | 1048576 -> 2097151 : 0 | | 2097152 -> 4194303 : 1 | | Picking 20us for the context-switch busyspin has the dual advantage of catching most frequent short waits while avoiding the cost of a context switch. 20us is a typical latency of 2 context-switches, i.e. the cost of taking the sleep, without the secondary effects of cache flushing. Signed-off-by: Chris Wilson Cc: Sagar Kamble Cc: Eero Tamminen Cc: Tvrtko Ursulin Cc: Ben Widawsky Cc: Joonas Lahtinen Cc: Michał Winiarski --- drivers/gpu/drm/i915/Kconfig.profile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/Kconfig.profile b/drivers/gpu/drm/i915/Kconfig.profile index 63cb744d920d..de394dea4a14 100644 --- a/drivers/gpu/drm/i915/Kconfig.profile +++ b/drivers/gpu/drm/i915/Kconfig.profile @@ -14,7 +14,7 @@ config DRM_I915_SPIN_REQUEST_IRQ config DRM_I915_SPIN_REQUEST_CS int - default 2 # microseconds + default 20 # microseconds help After sleeping for a request (GPU operation) to complete, we will be woken up on the completion of every request prior to the one