On Wed, May 15, 2013 at 06:01:42PM +0200, Patrik Rak wrote:
> Still waiting to hear some reason why what I propose is bad.
The various proposals are largely complementary. If we restrict
the slow path to 80% of the process limit, that's not too dramatic
a reduction (though slow mail should get more processes if possible,
espeically if this can be done *without* starving fast mail).
I am more concerned with the idea to limit deferred queue scans
when 80% of the active queue is previously deferred, while continuing
to take in new mail exclusively. This is a not a good idea.
Postfix already exerts too little back-pressure when the queue
fills, ignoring the deferred queue while taking more new mail
quickly will eliminate most of that (when the incoming queue is
not growing, there is no inflow_delay).
So I would definitely NOT cap the deferred queue fraction of the
active queue and favour new mail, unless stiffer back-pressure is
applied to new input (cleanup, ...) upstream. Yes we should quickly
process what we accepted, but we really should reduce our appetite
for new mail when the queue is already very large.
--
Viktor.
