From: David Airlie <airlied@redhat.com>
To: jdelvare@suse.de
Cc: christian.koenig@amd.com, "Iwai, Takashi" <tiwai@suse.de>,
dri-devel <dri-devel@lists.freedesktop.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Performance regression in ast drm driver
Date: Fri, 9 Nov 2018 10:04:03 +1000 [thread overview]
Message-ID: <CAMwc25oWstf8bFfWfb=FFR8GfFhx+jM77TzqE-qfi+ev2pMvFw@mail.gmail.com> (raw)
In-Reply-To: <20181108130509.3b2d42ff@endymion>
On Thu, Nov 8, 2018 at 10:05 PM Jean Delvare <jdelvare@suse.de> 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.
next prev parent reply other threads:[~2018-11-09 0:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 15:27 Performance regression in ast drm driver Jean Delvare
2018-11-08 12:05 ` Jean Delvare
2018-11-09 0:04 ` David Airlie [this message]
2018-11-10 8:39 ` Jean Delvare
2018-11-12 14:36 ` Jean Delvare
2018-11-12 14:45 ` Takashi Iwai
2018-11-12 16:41 ` Jean Delvare
2018-11-13 9:23 ` Thomas Zimmermann
2018-11-13 12:08 ` Jean Delvare
2018-11-13 12:16 ` Thomas Zimmermann
2018-11-12 19:36 ` Thomas Zimmermann
2018-11-13 8:19 ` YC Chen
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