On Wed, Sep 22, 2004 at 11:00:05AM +1200, Juha Saarinen said:
> Hope this isn't going to be a "Doctor, doctor, it hurts when I bang my
> head against the well" type of query, but... I've noticed on FreeBSD
> 5.3beta that Exim refuses connections if load averages shoot up:
>
> 2004-09-22 10:24:41 Connection from [202.150.102.34] refused: load
> average = 24.96
> 2004-09-22 10:24:52 Connection from [202.150.102.34] refused: load
> average = 25.07
> 2004-09-22 10:25:17 Connection from [204.127.198.39] refused: load
> average = 24.63
> 2004-09-22 10:29:02 Connection from [202.150.102.34] refused: load
> average = 12.05
>
> Had a look at daemon.c below, and kept an eye on the load averages
> with top and systat, and it seems as soon as the load goes over 10,
> Exim refuses connections.
>
> Unscientific testing of different apps indicates that the system is as
> responsible as under lighter loads as under ~20-25 loads so I wonder
> if Exim is "overreacting" here?
Taken from spec.txt:
$load_average: This variable contains the system load average, multiplied by
1000 to that it is an integer. For example, if the load average is 0.21, the
....
"deliver_queue_load_max" no queue deliveries if load high
"queue_only_load" queue incoming if load high
"smtp_load_reserve" SMTP from reserved hosts if load high
"smtp_load_reserve" only reserve hosts if this load
"queue_only_load" no immediate delivery if load is high
You'll want to set some of these to appropriate levels for your system.
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