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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 58690C49ED7 for ; Mon, 16 Sep 2019 09:06:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3432C20890 for ; Mon, 16 Sep 2019 09:06:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731648AbfIPJGY (ORCPT ); Mon, 16 Sep 2019 05:06:24 -0400 Received: from mga03.intel.com ([134.134.136.65]:12930 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726818AbfIPJGY (ORCPT ); Mon, 16 Sep 2019 05:06:24 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Sep 2019 02:06:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,512,1559545200"; d="scan'208";a="361466380" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.147.113]) by orsmga005.jf.intel.com with ESMTP; 16 Sep 2019 02:06:21 -0700 Date: Mon, 16 Sep 2019 17:06:52 +0800 From: Feng Tang To: Thomas Zimmermann Cc: Rong Chen , Stephen Rothwell , michel@daenzer.net, lkp@01.org, linux-kernel@vger.kernel.org, dri-devel Subject: Re: [LKP] [drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression Message-ID: <20190916090652.GK5541@shbuild999.sh.intel.com> References: <20190813093616.GA65475@shbuild999.sh.intel.com> <64d41701-55a4-e526-17ae-8936de4bc1ef@suse.de> <20190824051605.GA63850@shbuild999.sh.intel.com> <1b897bfe-fd40-3ae3-d867-424d1fc08c44@suse.de> <44029e80-ba00-8246-dec0-fda122d53f5e@suse.de> <90e78ce8-d46a-5154-c324-a05aa1743c98@intel.com> <2e1b4d65-d477-f571-845d-fa0a670859af@suse.de> <20190904062716.GC5541@shbuild999.sh.intel.com> <6806e973-4cf7-bcac-54b4-4fac21698ece@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6806e973-4cf7-bcac-54b4-4fac21698ece@suse.de> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, On Mon, Sep 09, 2019 at 04:12:37PM +0200, Thomas Zimmermann wrote: > Hi > > Am 04.09.19 um 08:27 schrieb Feng Tang: > > Hi Thomas, > > > > On Wed, Aug 28, 2019 at 12:51:40PM +0200, Thomas Zimmermann wrote: > >> Hi > >> > >> Am 28.08.19 um 11:37 schrieb Rong Chen: > >>> Hi Thomas, > >>> > >>> On 8/28/19 1:16 AM, Thomas Zimmermann wrote: > >>>> Hi > >>>> > >>>> Am 27.08.19 um 14:33 schrieb Chen, Rong A: > >>>>> Both patches have little impact on the performance from our side. > >>>> Thanks for testing. Too bad they doesn't solve the issue. > >>>> > >>>> There's another patch attached. Could you please tests this as well? > >>>> Thanks a lot! > >>>> > >>>> The patch comes from Daniel Vetter after discussing the problem on IRC. > >>>> The idea of the patch is that the old mgag200 code might display much > >>>> less frames that the generic code, because mgag200 only prints from > >>>> non-atomic context. If we simulate this with the generic code, we should > >>>> see roughly the original performance. > >>>> > >>>> > >>> > >>> It's cool, the patch "usecansleep.patch" can fix the issue. > >> > >> Thank you for testing. But don't get too excited, because the patch > >> simulates a bug that was present in the original mgag200 code. A > >> significant number of frames are simply skipped. That is apparently the > >> reason why it's faster. > > > > Thanks for the detailed info, so the original code skips time-consuming > > work inside atomic context on purpose. Is there any space to optmise it? > > If 2 scheduled update worker are handled at almost same time, can one be > > skipped? > > We discussed ideas on IRC and decided that screen updates could be > synchronized with vblank intervals. This may give some rate limiting to > the output. > > If you like, you could try the patch set at [1]. It adds the respective > code to console and mgag200. I just tried the 2 patches, no obvious change (comparing to the 18.8% regression), both in overall benchmark and micro-profiling. 90f479ae51afa45e 04a0983095feaee022cdd65e3e4 ---------------- --------------------------- 37236 ± 3% +2.5% 38167 ± 3% vm-scalability.median 0.15 ± 24% -25.1% 0.11 ± 23% vm-scalability.median_stddev 0.15 ± 23% -25.1% 0.11 ± 22% vm-scalability.stddev 12767318 ± 4% +2.5% 13089177 ± 3% vm-scalability.throughput Thanks, Feng > > Best regards > Thomas > > [1] > https://lists.freedesktop.org/archives/dri-devel/2019-September/234850.html > > > > > Thanks, > > Feng > > > >> > >> Best regards > >> Thomas > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany > GF: Felix Imendörffer, Mary Higgins, Sri Rasiah > HRB 21284 (AG Nürnberg) >