Re: Not MTRR !? was: ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2

From: Rik van Riel (riel@conectiva.com.br)
Date: Wed Mar 28 2001 - 08:54:42 EST


On Wed, 28 Mar 2001, Robert Suetterlin wrote:

> As far as I can see almost all memory is set write-back. The memory at
> the far end belongs to some hardware, see /proc/iomem below.

> reg00: base=0xfb000000 (4016MB), size= 16MB: uncachable, count=1
> reg01: base=0xfc000000 (4032MB), size= 64MB: uncachable, count=1
> reg02: base=0x00000000 ( 0MB), size=8192MB: write-back, count=1
> reg03: base=0x200000000 (8192MB), size=4096MB: write-back, count=1
> reg04: base=0x300000000 (12288MB), size=2048MB: write-back, count=1
> reg05: base=0x380000000 (14336MB), size=1024MB: write-back, count=1
> reg06: base=0x3c0000000 (15360MB), size= 512MB: write-back, count=1
> reg07: base=0x3e0000000 (15872MB), size= 256MB: write-back, count=1
                                           ------ +
                                          15.75 GB

It looks like the last 256MB isn't cached (well, it doesn't
have an MTRR at all) and Linux starts loading programs from
the top of memory ...

regards,

Rik

--
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

http://www.surriel.com/ http://www.conectiva.com/ http://distro.conectiva.com.br/

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This archive was generated by hypermail 2b29 : Sat Mar 31 2001 - 21:00:18 EST