linux-kernel - Re: Performance regression in ast drm driver

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Message-ID: <89ae9adf-27e7-ae80-639c-c67202a0d0b7@suse.de>
Date:   Tue, 13 Nov 2018 10:23:45 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Jean Delvare <jdelvare@...e.de>, Takashi Iwai <tiwai@...e.de>
Cc:     David Airlie <airlied@...hat.com>, christian.koenig@....com,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Performance regression in ast drm driver

Jean,

ast doesn't remove the vesafb's framebuffer before attaching to the
device. I have a patch at [1]. If you have a way of testing it, I'd
appreciate.

Best regards
Thomas

[1] https://bugzilla.suse.com/show_bug.cgi?id=1112963

Am 12.11.18 um 17:41 schrieb Jean Delvare:
> On Mon, 2018-11-12 at 15:45 +0100, Takashi Iwai wrote:
>> On Mon, 12 Nov 2018 15:36:07 +0100,
>> Jean Delvare wrote:
>>> 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...
> 
> Yes, I double checked and can only confirm what I wrote above. However
> while checking I noticed another strange thing: the contents of
> pat_memtype_list depend on whether I'm reading the file from an xterm
> or from the text console (Ctrl+Alt+F2). So I summarize again:
> 
> Commit "drm/drivers: add support for using the arch wc mapping API"
> APPLIED, reading pat_memtype_list from the text console:
> 
> uncached-minus @ 0xfafe0000-0xfb000000
> uncached-minus @ 0xfb000000-0xfb005000
> uncached-minus @ 0xfb000000-0xfb800000
> uncached-minus @ 0xfb005000-0xfb584000
> 
> Commit "drm/drivers: add support for using the arch wc mapping API"
> APPLIED, reading pat_memtype_list from an xterm:
> 
> uncached-minus @ 0xfafe0000-0xfb000000
> uncached-minus @ 0xfb000000-0xfb005000
> uncached-minus @ 0xfb000000-0xfb800000
> 
> Commit "drm/drivers: add support for using the arch wc mapping API"
> REVERTED, reading pat_memtype_list from the text console:
> 
> uncached-minus @ 0xfafe0000-0xfb000000
> uncached-minus @ 0xfb000000-0xfb005000
> write-combining @ 0xfb005000-0xfb584000
> 
> Commit "drm/drivers: add support for using the arch wc mapping API"
> REVERTED, reading pat_memtype_list from an xterm:
> 
> uncached-minus @ 0xfafe0000-0xfb000000
> uncached-minus @ 0xfb000000-0xfb005000
> 
> If you don't find it logical, remember that if things were the way they
> are supposed to be, customers and myself would not be reporting this
> bug ;-)
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstr. 5, D-90409 Nürnberg
Tel: +49-911-74053-0; Fax: +49-911-7417755;  https://www.suse.com/
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard,
Graham Norton, HRB 21284 (AG Nürnberg)



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