Re: Best way to use more that 4 gigs of memory ?

Hi,

On 4 Nov 2007, at 21:11, Pete French wrote:

I have been doing some experiments with runnign 32 bit processed on
and amd64 kernel over the last couple of days and am wondering what
the general feel is for the best way to use over 4 gigs of memory. As far
as I can see I have 3 options:

1) amd64 kernel + 64 bit processes
2) amd64 kernel + 32 bit processes
3) i386 kernel with PAE and 32 bit processes

I was initially thinking that option 1 was the best, but benchmarking it
the programs take 3 times longer to run that option 2! This astounds me
and I intend to investigate why, but given it is rue then that rules it out
as a viable solution for deploying stuff.

I had similar results, I surmise (without evidence) it's to do with cache usage.

Which leaves either 32 bit processes on a 64 bit kernel or alternatively
running under PAE on a 32 bit kerenel. I don't know a lot about PAE and
was wondering if anyone had any advice either way as to which wouldbe the most
stable and/or best performing.

If your workload is CPU-intensive it probably doesn't matter; if it isn't, I'd do some more experiments.

cheers,

-pcf.



--
Bob Bishop +44 (0)118 940 1243
rb@xxxxxxxxx fax +44 (0)118 940 1295




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