ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2

ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2

[Robert Suetterlin]

Hello,

ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2
DESCR: we have a Maxdata 4-way Xeon, with 16GByte RAM. If we compile a kernel (2.4.0 or 2.4.2 up to ac25) that uses all 16 GByte RAM the machine gets very slow. For example network Bandwidth of 100MBit Ethernet is about 1-50kByte/sec.  Access to harddrives seems to be equally slow.
	I really do not know where to start looking, but I know that lots of people seem to be using n-way Xeon with 16+GByte RAM without severe performance problem.
KEYWORDS: kernel, slow, maxdata, 16GB
KERNEL: 2.4.0 and 2.4.2 (upto ac25)

If more information --- like /proc/cpuinfo or uname -a or versions of installed software ... --- is needed to analyse the problem, please tell me, I will gladly send it.

Sincerely,

	Robert S.

Re: ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2

[Rik van Riel]

On Tue, 27 Mar 2001, Robert Suetterlin wrote:

> ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2

Last time we saw this issue on the list it turned out that the
machine had wrong MTRR settings and setup a significant part of
its memory non-cachable.

For a 16-way machine, 100 times speed difference is exactly what
I would expect when all memory is setup as uncachable.

regards,

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

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