Timo Sirainen wrote:
On Tue, 2005-12-06 at 08:02 -0500, Stewart Dean wrote:
Much of my aggravations with user use/misuse/stupidity traces back to this simple fact: there is rarely any feedback mechanism in server apps to indicate to the user the loads their practices cause. It is as if they were driving a car without a gas gauge, if they had bodies that didn't feel pain. /I/ wish that there was some metric that could tell a user the composite CPU and memory loads their mail usage represents.
Hmm. I'm not sure if such loads can be told to use in any easy way. But I've been thinking about having a plugin that could tell admin what's happening in the computer. What imap/pop3 processes are using all the disk I/O, memory and CPU and what exactly they're doing, and if there are some special conditions (eg. broken indexes causing the load, etc).
I've been using pacct/acctcom etc. on Solaris to give per-process CPU usage, disk block count, and kcore minutes. It's a bit fiddly though!
Talking of which, I've been trying IMAP SSL using both Perdition as a proxy to a Dovecot without SSL support, and Dovecot directly with SSL support and, to my surprise, found Dovecot-SSL using much more CPU for longer-lived processes (as much in an afternoon as my username usually uses in a week!). The Perdition proxy method seems to add a 30-50% overhead to the CPU load. I need to get some more users to test it all, though!
Best Wishes, Chris
-- --+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+- Christopher Wakelin, c.d.wakelin@reading.ac.uk IT Services Centre, The University of Reading, Tel: +44 (0)118 378 8439 Whiteknights, Reading, RG6 2AF, UK Fax: +44 (0)118 975 3094