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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 E476FC43441 for ; Mon, 12 Nov 2018 14:45:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC77D2245E for ; Mon, 12 Nov 2018 14:45:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC77D2245E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728281AbeKMAjF (ORCPT ); Mon, 12 Nov 2018 19:39:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:38314 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726385AbeKMAjF (ORCPT ); Mon, 12 Nov 2018 19:39:05 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id D65BCB136; Mon, 12 Nov 2018 14:45:29 +0000 (UTC) Date: Mon, 12 Nov 2018 15:45:29 +0100 Message-ID: From: Takashi Iwai To: Jean Delvare Cc: David Airlie , christian.koenig@amd.com, dri-devel , linux-kernel Subject: Re: Performance regression in ast drm driver In-Reply-To: <1542033367.2661.33.camel@suse.de> References: <20181101162707.598c1718@endymion> <20181108130509.3b2d42ff@endymion> <1542033367.2661.33.camel@suse.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/26 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 12 Nov 2018 15:36:07 +0100, Jean Delvare wrote: > > Hi David, > > On Fri, 2018-11-09 at 10:04 +1000, David Airlie wrote: > > On Thu, Nov 8, 2018 at 10:05 PM Jean Delvare wrote: > > > > > > On Thu, 1 Nov 2018 16:27:07 +0100, Jean Delvare wrote: > > > > Hi David, > > > > > > > > The following commit: > > > > > > > > commit 7cf321d118a825c1541b43ca45294126fd474efa > > > > Author: Dave Airlie > > > > Date: Mon Oct 24 15:37:48 2016 +1000 > > > > > > > > drm/drivers: add support for using the arch wc mapping API. > > > > > > > > is causing a huge performance regression for the ast drm driver. In a > > > > text console, if I call "cat" on a large text file, it takes almost > > > > twice as much time to be displayed and scrolled completely. > > > > > > > > Can you please check that the ast driver portion of that commit is both > > > > correct and complete? > > > > > > And in the meantime, what bad will happen if we just revert the ast > > > portion of that commit? > > > > This seems likely to be a hw problem with PCI writes to the AST "GPU", > > since it's just some sort of RAM + ARM on the end of a PCIE bus, we've > > definitely seen possible issues in the past with write combining > > around some of the mga GPUs with some CPUs. > > Takashi asked me to compare the contents of > /sys/kernel/debug/x86/pat_memtype_list before and after the commit > above. Before the commit, we have: > > uncached-minus @ 0xfafe0000-0xfb000000 > uncached-minus @ 0xfb000000-0xfb005000 > write-combining @ 0xfb005000-0xfb584000 > > After the commit, we have: > > uncached-minus @ 0xfafe0000-0xfb000000 > uncached-minus @ 0xfb000000-0xfb005000 > uncached-minus @ 0xfb000000-0xfb800000 > uncached-minus @ 0xfb005000-0xfb584000 Just to be sure: could you double-check whether you're checking the right order (i.e. not checking against the revert)? The change above looks illogical from what I can see from the commit... thanks, Takashi > > The corresponding lines in /proc/iomem are: > > f0000000-fed8ffff : PCI Bus 0000:00 >   faf00000-fb7fffff : PCI Bus 0000:01 >     fafe0000-faffffff : 0000:01:01.0 >     fb000000-fb7fffff : 0000:01:01.0 > > Does it help? Is the change of type expected? Is it not a problem that > one of the ranges is overlapping with 2 other ranges? > > -- > Jean Delvare > SUSE L3 Support >