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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 8AF60C43331 for ; Fri, 3 Apr 2020 16:17:21 +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 4CB3820721 for ; Fri, 3 Apr 2020 16:17:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4CB3820721 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 CF7C66EC19; Fri, 3 Apr 2020 16:17:20 +0000 (UTC) Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 06A966EC19 for ; Fri, 3 Apr 2020 16:17:18 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from localhost (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP (TLS) id 20791312-1500050 for multiple; Fri, 03 Apr 2020 17:17:16 +0100 MIME-Version: 1.0 In-Reply-To: <20200403010120.3067-1-ashutosh.dixit@intel.com> References: <20200403010120.3067-1-ashutosh.dixit@intel.com> From: Chris Wilson To: Ashutosh Dixit , intel-gfx@lists.freedesktop.org Message-ID: <158593063457.5852.4620122096592068466@build.alporthouse.com> User-Agent: alot/0.8.1 Date: Fri, 03 Apr 2020 17:17:14 +0100 Subject: Re: [Intel-gfx] [PATCH] drm/i915/perf: Do not clear pollin for small user read buffers 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Quoting Ashutosh Dixit (2020-04-03 02:01:20) > It is wrong to block the user thread in the next poll when OA data is > already available which could not fit in the user buffer provided in > the previous read. In several cases the exact user buffer size is not > known. Blocking user space in poll can lead to data loss when the > buffer size used is smaller than the available data. > > This change fixes this issue and allows user space to read all OA data > even when using a buffer size smaller than the available data using > multiple non-blocking reads rather than staying blocked in poll till > the next timer interrupt. > > v2: Fix ret value for blocking reads (Umesh) > v3: Mistake during patch send (Ashutosh) > v4: Remove -EAGAIN from comment (Umesh) > v5: Improve condition for clearing pollin and return (Lionel) > v6: Improve blocking read loop and other cleanups (Lionel) > v7: Added Cc stable > > Cc: Umesh Nerlige Ramappa > Cc: > Reviewed-by: Lionel Landwerlin > Signed-off-by: Ashutosh Dixit Did you manage to devise a test case? It is nice (some might say important) to pair a patch for stable with its regression test. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx