linux-kernel - Re: [Bug 10328] New: [regression] performance drop for glx

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Message-Id: <1209101723.21553.1.camel@zwerg>
Date:	Fri, 25 Apr 2008 07:35:23 +0200
From:	Alexey Fisher <bug-track@...her-privat.net>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	bugme-daemon@...zilla.kernel.org, linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rjw@...k.pl>, venkatesh.pallipadi@...el.com
Subject: Re: [Bug 10328] New: [regression] performance drop for glx

Am Dienstag, den 25.03.2008, 21:42 -0700 schrieb Arjan van de Ven:
> Suresh Siddha wrote:
> > On Tue, Mar 25, 2008 at 03:28:09PM -0700, Andrew Morton wrote:
> >> (switched to email.  Please respond via emailed reply-to-all, not via the
> >> bugzilla web interface).
> >>
> >> On Tue, 25 Mar 2008 15:11:15 -0700 (PDT)
> >> bugme-daemon@...zilla.kernel.org wrote:
> >>
> >>> http://bugzilla.kernel.org/show_bug.cgi?id=10328
> >>>
> >>>            Summary: [regression] performance drop for glx
> >>>
> >>> after commit 4138cc3418f5eaa7524ff8e927102863f1ba0ea5 i expirience some grafik
> >>> related perfomance issues.
> >>>
> >>> I used glxgears for test.
> >>> before this patch: 1281.005 FPS
> >>> and after: 765.000 FPS
> >> It nearly halved.
> >>
> >>> latest tested commit a4083c9271e0a697278e089f2c0b9a95363ada0a
> >>> still hase bad performance.
> >>>
> >>> I use Pentium D with 2GB RAM, Grafick: i945G, ICH7
> >>>
> >> That's 
> >>
> >> : commit 4138cc3418f5eaa7524ff8e927102863f1ba0ea5
> >> : Author: Siddha, Suresh B <suresh.b.siddha@...el.com>
> >> : Date:   Wed Jan 30 13:33:43 2008 +0100
> >> : 
> >> :     x86: set strong uncacheable where UC is really desired
> >> :     
> >> :     Also use _PAGE_PWT for all the mappings which need uncache mapping.
> >> :     Instead of existing PAT2 which is UC- (and can be overwritten by MTRRs),
> >> :     we now use PAT3 which is strong uncacheable.
> >> :     
> >> :     This makes it consistent with pgprot_noncached()
> > 
> > Alexey, Can you please try the appended patch?
> > 
> > Andrew, can you please push the appended patch for 2.6.25? Thanks.
> > ---
> > 


This issue come again with commit:

commit 2e5d9c857d4e6c9e7b7d8c8c86a68a7842d213d6
Author: venkatesh.pallipadi@...el.com <venkatesh.pallipadi@...el.com>
Date:   Tue Mar 18 17:00:14 2008 -0700

    x86: PAT infrastructure patch

    Sets up pat_init() infrastructure.

    PAT MSR has following setting.
        PAT
        |PCD
        ||PWT
        |||
        000 WB          _PAGE_CACHE_WB
        001 WC          _PAGE_CACHE_WC
        010 UC-         _PAGE_CACHE_UC_MINUS
        011 UC          _PAGE_CACHE_UC

    We are effectively changing WT from boot time setting to WC.
    UC_MINUS is used to provide backward compatibility to existing /dev/mem
    users(X).

    reserve_memtype and free_memtype are new interfaces for maintaining
alias-free
    mapping. It is currently implemented in a simple way with a linked list and
    not optimized. reserve and free tracks the effective memory type, as a
result
    of PAT and MTRR setting rather than what is actually requested in PAT.

    pat_init piggy backs on mtrr_init as the rules for setting both pat and
mtrr
    are same.

    Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
    Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
    Signed-off-by: Ingo Molnar <mingo@...e.hu>

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