Roundcube performance

[Toke Høiland-Jørgensen]

Enrico Tagliavini <enrico.tagliavini at gmail.com> writes:

> But adding a proxy, so that connection to the imap server is kept for
> a long time, is removing this delay. Which probably means imapd is
> actually fast reading messages from the disk, or preloads them (no
> idea about this, just a guess). So what probably is slow is the
> operations just after a user login, does this makes sense? I have
> prefork set to 10 on imapd in cyrus.conf I don't have much clues about
> how cyrus imap works, so any advise to make it a little bit faster, in
> a 3 users scenario, is appreciated.

This sounds like it might be related to the 'lock' and 'proc' files that
cyrus-imapd creates on every user login. I seem to recall having
horrible performance because of that at some point.

Basically, imapd creates a pid file in /var/lib/imap/proc on every
login, and a lock file in /var/lib/imap/lock on every folder access. If
the server is IOPS-limited this can cause large delays. The solution (if
this is indeed what you're experiencing) is to move these directories to
tmpfs; either symlink them into an existing tmpfs (such as /dev/shm or
/tmp depending on your setup), or stick this in your /etc/fstab:

none /var/lib/imap/proc tmpfs defaults 0 0
none /var/lib/imap/lock tmpfs defaults 0 0

and then mount the directories.


-Toke
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