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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 92FB2C2D0F6 for ; Wed, 16 Sep 2020 08:34:30 +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 3F875206DC for ; Wed, 16 Sep 2020 08:34:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="vI336rtD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3F875206DC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org 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 9FE466E3A6; Wed, 16 Sep 2020 08:34:28 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5BA096E391 for ; Wed, 16 Sep 2020 08:34:27 +0000 (UTC) Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9CDAF20795; Wed, 16 Sep 2020 08:34:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600245267; bh=5KLkA+J2/h4eyGXRPb1P2FQzvzNuKGk/+COHN+p/Ppk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vI336rtD1Shh6hNtyvcoudIm1LkDtc5bt5bmYZ5Dp2UHKGu95jAcATPJff75z82Wj CCkhnImzgGirdmdsNURNuDKKTcs+MuOk/WXRz/FjfT1knQGDGOguEqqsgnC8yUMLs1 VZdZez1PU6f9/qRX4pFcq36uldf4/ngIc3lzee04= Date: Wed, 16 Sep 2020 10:35:01 +0200 From: Greg KH To: Chris Wilson Message-ID: <20200916083501.GA675213@kroah.com> References: <20200915124150.12045-1-chris@chris-wilson.co.uk> <20200915124150.12045-2-chris@chris-wilson.co.uk> <20200916063358.GL142621@kroah.com> <160024481825.2231.4268855132793535750@build.alporthouse.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <160024481825.2231.4268855132793535750@build.alporthouse.com> Subject: Re: [Intel-gfx] [PATCH 2/4] drm/i915/gt: Wait for CSB entries on Tigerlake 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: intel-gfx@lists.freedesktop.org, stable@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Wed, Sep 16, 2020 at 09:26:58AM +0100, Chris Wilson wrote: > Quoting Greg KH (2020-09-16 07:33:58) > > On Tue, Sep 15, 2020 at 01:41:48PM +0100, Chris Wilson wrote: > > > On Tigerlake, we are seeing a repeat of commit d8f505311717 ("drm/i915/icl: > > > Forcibly evict stale csb entries") where, presumably, due to a missing > > > Global Observation Point synchronisation, the write pointer of the CSB > > > ringbuffer is updated _prior_ to the contents of the ringbuffer. That is > > > we see the GPU report more context-switch entries for us to parse, but > > > those entries have not been written, leading us to process stale events, > > > and eventually report a hung GPU. > > > > > > However, this effect appears to be much more severe than we previously > > > saw on Icelake (though it might be best if we try the same approach > > > there as well and measure), and Bruce suggested the good idea of resetting > > > the CSB entry after use so that we can detect when it has been updated by > > > the GPU. By instrumenting how long that may be, we can set a reliable > > > upper bound for how long we should wait for: > > > > > > 513 late, avg of 61 retries (590 ns), max of 1061 retries (10099 ns) > > > > > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2045 > > > References: d8f505311717 ("drm/i915/icl: Forcibly evict stale csb entries") > > > > What does "References:" mean? Should that be "Fixes:"? > > It's a reference to an earlier w/a for a previous generation for the > same symptoms. This patch should supplement that w/a. I see no such "reference" to that tag in Documentation/process/submitting-patches.rst, so how were we supposed to know this? :) thanks, greg k-h _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx