[Mimedefang] Some observations while using MIMEDefang 2.35

[Jason Gurtz]

Hi all,

	Just thought I'd share some performance observations since using 2.35
in production for a few weeks now after testing on my home machine.

	I've taken advantage of the queuing feature and am using the following
startup for the multiplexor (also w/ appropriate -s and -p options):

/mimedefang-multiplexor -x 2 -m 2 -q 10 -Q 30 -r 50 -b 60 -i 120

	The machine is a P1-166MMX w/256MB RAM and IDE I/O running Linux-2.4.19
ext3 fs. and Spamassassin 2.54  The box serves secure webmail w/
SquirrelMail and normal POP3 to a couple dozen users.  About 3-6
thousand messages come through most days (copious mailing lists :).  And
the box generaly get's a good working out due to the many cpu and I/O
intensive services.  There is no virus scanner and we use MIMEDefang
mostly to filter out bad attachments and run SA.  Due to the naughty
bosses, html mails have to go through :/

	Usualy the load sits between .25-.75 during the workday but occasionly
takes excursions to 1 and beyond.  We've had issues in the past where
the load got to great and mail was piling up on backup MX's.  Today I
watched a user abusing the box trying to repeatedly send webmail to a
non-allowed address and saw the load go over 4.2 for a number of
minutes.  During this time I was pleased to note that
MIMEDefang/Spamassassin continued to function in a correct manner on
incoming mail and no mail was piling up on the BU MX's  =)  This
definatly would not have been the case pre-queuing.  Also, in general,
the load has tended to be much more often around the low end of .25-.75
where as before, it was seemed to be more in the .6-.9 range much of the
time.

	On a more general, tuning related, note it seems best to use just 2
childeren on this slow box.  I tried running up to 5 with longer
timeouts but that would seriously overwhelm the box when a flood of
mails from e.g. LKML came in.  Sometimes spiking the load >12, fun fun ;)

Best Regards,

~Jason

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