At 04:27 PM Friday 4/9/99, Sam wrote:
>Dave Sill writes:
>
>> >> When you're sending messages, how many qmail-remotes are running?
>> >
>> >About 90-130. 255 if I stop delivery for a little while and then restart
>> >it. To me that means that the machine can send faster then I can get the
>> >messages into the queue.
>>
>> That's what it sounds like. So you either need to speed up the
>> existing process via h/w or s/w changes, or modify the injection
>> process.
>
>I find this very difficult to believe, that it takes longer to add
>something to the queue than to make several DNS queries, establish a
>socket, and go through the SMTP handshake in order to deliver the message.
I don't find it particularly hard to believe. queue-insertion is expension
on the file system and slow if the file system is busy with 100s of outbound
deliveries (of individual mails).
At, say, 200K per hour, that's 50 queue insertions per second and 50 queue
removals per second. That's starting to be a lot of I/O.
>If you're injecting messages one at a time, it is possible that fsyncs and
>the rest of the disk activity are throttling your input, but I still find
>it somewhat difficult to swallow. However that's the only possible answer
>in absence of a resource shortage. You should be able to remedy that by
>injecting multiple messages in parallel.
I doubt it. He's probably out of disk thruput.
Of course presenting iostats and vmstats whilst the processes are running
would clear a lot of that up.
Regards.
