On Mon, Feb 07, 2022 at 03:11:25PM +0100, Víctor Rubiella Monfort wrote:
> We can increase smtp easly to 1000 connections for example to allow
> multiple incoming connections.
When you raise the number of "smtp inet ... smtpd" process slots the you
just need to ensure that your disk and network are fast enough to not
thrash under that load, and make sure that the *output* delivery agents
can keep up.
* If you have a content filter or milter in place, make sure it
has enough CPU capacity/concurrency.
* If you're delivering to a separate mailstore, make sure you have
enough output concurrency to keep the remote busy without
overwhelming it. (May need to raise the destination concurrency
limit on the "relay" transport).
> I'm supose the best approach depends of a lot of diferent inpunts, but
> in general there are some tips to consider increase this values?, for
> example mantain the ratios 1/10 etc.. ? Prevent bottlenecks, excesive
> cpu/memory consumption increasing one of this procs,etc...
The basic fact of life is:
Throughput = Concurrency / Latency
You need to keep the steady-state input capacity below the available
peak output capacity. If the input arrives faster than you can process
it, you get congestive collapse.
And, of course, once all your CPUs are saturated with content filtering,
you can't get more throughput by raising concurrency, all that happens
is that per message latency goes up, and throughput eventually goes down
due to thrashing.
--
Viktor.
