On Fri, Sep 26, 2008 at 06:30:03PM +0300, Marco TCHI HONG wrote:
> >These concurrency numbers are very high. Running A/V scanning
> >at concurrency substantially higher than ~20 (on Dual CPU boxes) is
> >generally counter-productive.
>
> I have two Xeon 5160 Dual-Core 3,0 GHz on my box and 4Gb RAM.
> About 500k mail go through this MX (50Gb traffic).
>
> >What is the destination concurrency limit for mail heading to the
> >"kas-pipe" process?
>
> Right now it is set to 200. Well it was set to 40 before the problem
> appeared, but I increased it ... because I thought it was the problem.
The client concurrency must not exceed the service concurrency, and
virus scanning is CPU intensive, and in my experience this is too much.
Of course in a multi-filter chain, if any of the filters are high
latency, the combined filter latency can throttle the CPU demand
of any CPU intensive stage, and in that case, higher concurrency
may be appropriate, but if filters in a chain have vastly different
characteristics (impedance mismatch), it may be appropriate to
insert a Postfix queue in between:
Postfix -> filter1 -> Postfix -> filter2 -> Postfix ...
Each Postix stage (except the last) sets a suitable content filter, has
appropriate concurrency settings, ...
--
Viktor.
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