On Fri, 16 Feb 2007, Timo Sirainen wrote:
Date: Fri, 16 Feb 2007 13:39:33 +0200 From: Timo Sirainen <tss@iki.fi> To: Dan Price <dp@eng.sun.com> Cc: dovecot@dovecot.org Subject: Re: [Dovecot] severe performance problem (mail cache related?)
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.
Dan,
Could you give us other Sun users a few details of your setup, so wecan avoid this hole? I am running rc22 on a T2000, Solaris 10 11/06 plus (mostly) current patches, ZFS version 3 for my user homedirs (where cache files and folders go), INBOXes NFS mounted from another Sun S10 box (NFS version 4). I have never touched any of the mmap related settings in dovecot.conf. The whole thing works beautifully for 3000 users. The T2000 never breaks a sweat. The users are happy.
Jeff Earickson Colby College