Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH 1/5] cpuset memory spread basic implementation | Date | Tue, 7 Feb 2006 18:26:17 +0100 |
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On Tuesday 07 February 2006 18:06, Christoph Lameter wrote: > On Tue, 7 Feb 2006, Ingo Molnar wrote: > > > * Andi Kleen <ak@suse.de> wrote: > > > > > I still don't really think it will make much difference if the file > > > cache is local or global. Compare to disk IO it is still infinitely > > > faster, so a relatively small slowdown from going off node is not that > > > big an issue. > > > > well, maybe the SGI folks can give us some numbers? > > The latency may grow (average) by a factor of 4 (same thoughput though on > our boxes). On some architectures it is significantly more and also the > bandwidth is reduced. > > This is a significant factor. Applications that do not manage locality > correctly loose at least 30-40% performance.
This number is for local mapped memory I assume.
But do you have any numbers for file caches or dentry/inode caches? My guess is that if an application would lose that much in read/write or readdir/stat it would call them too often :) But it's unlikely i guess.
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