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 7F5AFC43441 for ; Fri, 9 Nov 2018 00:04:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44D5620855 for ; Fri, 9 Nov 2018 00:04:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44D5620855 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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 S1727615AbeKIJmQ (ORCPT ); Fri, 9 Nov 2018 04:42:16 -0500 Received: from mail-vs1-f50.google.com ([209.85.217.50]:41886 "EHLO mail-vs1-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727289AbeKIJmQ (ORCPT ); Fri, 9 Nov 2018 04:42:16 -0500 Received: by mail-vs1-f50.google.com with SMTP id t17so45350vsc.8 for ; Thu, 08 Nov 2018 16:04:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=CAk+1k0shuYGopg8VVtccJNGDqJOzQz7q3/ZAZfqn88=; b=oAhZmuGexP0m72k3+vCsfgxU68+wAP0Ozd1XCi1eg1OwFYKX5pclNQTzaAUc8eu/ib DeFjxGJ/6bDh6h0ZdTj++cGD+JAvsoIhISXbpBbiUi9itDXN5/pS44f44fMEYFwt0LkY hhIazgCHaXkiySc2rRFIrhxMD5PbjUqVWH9cMrpajk3hYvM0YJOBbqcMci6MxJlXQlAs 6a9WkllvnVlr6WT+xrS5Gj2+tecJRaUNwgMgQt8+RGiaOpdu2Rm/YfVh0WRcMX7keq02 wQU7RcEZI4Kwtll5MMigLUpTjO/2nRzGl9vSWypA4xikgP3mMPR1NexqlAe+ydPqS0ss oi1A== X-Gm-Message-State: AGRZ1gL85Fx+rE/oZMHUwhkDa59it1u249aHghudVYatArKZLThkTfzf hJZrFLFVvwoEir1lni9LZUnZyzAyWX7T27FiyOC8WA== X-Google-Smtp-Source: AJdET5fmi8nhtdaUB3SXVLxCytgm6Pk1Z9FW+tUV1rqmmfzum337OFBdK/x54yTeYF3RDAIU1Yn18go/IsPOV4XCz7U= X-Received: by 2002:a67:6e87:: with SMTP id j129mr2959928vsc.171.1541721855642; Thu, 08 Nov 2018 16:04:15 -0800 (PST) MIME-Version: 1.0 References: <20181101162707.598c1718@endymion> <20181108130509.3b2d42ff@endymion> In-Reply-To: <20181108130509.3b2d42ff@endymion> From: David Airlie Date: Fri, 9 Nov 2018 10:04:03 +1000 Message-ID: Subject: Re: Performance regression in ast drm driver To: jdelvare@suse.de Cc: christian.koenig@amd.com, "Iwai, Takashi" , dri-devel , linux-kernel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Have we seen the problem across a number of AST devices? Dave.