On 15.5.2013 17:44, Wietse Venema wrote:
What I recall is that queue lengths depend not only on AVERAGE
arrival rates. The variations in arrival rates make a huge difference,
as experienced daily with queues before ladies' bathrooms (yes I
am aware that ladies, unlike email, don't back off exponentially).
BTW, this one, no matter how humorous it may seem, is really spot on.
Like the ladies, I don't need a solution which works well on average.
New mail delivered quickly on average is not good enough. I need it
delivered quickly, period. If any new mail is delayed several minutes,
the harm is already done, however low the average delay might be.
That's the reason why Viktor's analysis about average rates, no matter
how enlightening and insightful it may be, doesn't provide usable
solution for this.
During the night I have also realized another problem regarding the
retry times. By adjusting those to defeat congestion, for the lack of
better controls, Victor deliberately and unconditionally affects the
delivery times of legal deferred mail at the same time. By preparing for
the worst, he may as well needlessly delay graylisted mail, regardless
of whether there is any congestion happening or not.
With the common presence of graylisting these days, I can't afford to
use the retry times in a questionable attempt to fight congestion. I
need them for what they are supposed to do - to control the retry times
of deferred mails. My goal is to deliver legal mail as quickly as
possible, be it graylisted or not. The graylisting timeouts range from
tens of seconds to several minutes, so I need short retry times to deal
with that. If I leave the minimum retry time set to 300s, I have already
lost the case.
Just thought I'd mention this, in case there is someone else still
following this thread who hasn't been bored to death by now... :)
Patrik
