Michael Brutman <brutman@???> wrote:
>
>Kernel profiling is telling me that it spends a lot of time creating
>processes - 60% of the CPU time is spent in kernel mode. I understand from
>reading the documentation and the archives that exim uses a delivery
>process for each delivery, and I suspect that it what is causing this.
I'm surprised that CPU is your limiter. Seymour Cray is supposed to have
said that a supercomputer is a device for turning a compute-bound process
into an IO-bound one, so perhaps you should just get bigger processors :-)
Alternatively, you might try using one big CPU instead of two smaller
ones to avoid SMP locking issues.
How many concurrent processes are you seeing? Perhaps you can reduce
context-switch thrashing by adjusting Exim's load management options.
I've done this by arranging for mail to be queued in high load situations,
and limited the number of queue runners (which is the same as the number
of concurrent deliveries of deferred mail).
Exim re-execs itself quite frequently in order to manage privilege
(especially for local deliveries), and because run-time linking slows
things down you will be better off with a statically-linked Exim.
Tony.
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