[Dovecot] severe performance problem (mail cache related?)

Timo Sirainen tss at iki.fi
Fri Feb 16 11:39:33 UTC 2007


On Fri, 2007-02-16 at 03:29 -0800, Dan Price wrote:
> > Yes, and it's done as long as you don't have mmap_disable=yes. Hmm.
> > Weren't you using ZFS directly? Why are you using mmap_disable=yes? :)
> > Its main purpose is to make indexes work in NFS.
> 
> Well there you go, I'm a dope.  I think I set mmap_disable=yes because I
> was seeing strange things happening where there would be thousands
> (millions?) of madvise(DONTNEED) calls-- seemingly forever in a loop.  I
> have not yet tracked that problem down-- next time I see it, I will
> make sure to get to the bottom of it.

Actually the only place where madvise(MADV_DONTNEED) is called is in the
file-cache code which is used only with mmap_disable=yes.

There are madvise(MADV_SEQUENTIAL) calls with mmap_disable=no though.

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