Nikolai Dahlem:
[inbound SMTP]
> delay=0.51, delays=0.21/0/0.17/0.13
Just to be sure, these numbers include receiving and delivering mail.
0.21 time from message arrival to last active queue entry
0 time from last active queue entry to connection setup
0.17 time in connection setup, including DNS, EHLO and STARTTLS
0.13 time in message transmission
The first number shows that it takes 0.2s to put mail into the
queue. Does your host run a LOCAL caching DNS server? If not, that
could explain sluggish performance for receiving and sending mail.
When receiving SMTP mail, Postfix looks up IPaddress->name and
name->IPaddress which can result in two DNS queries per inbound
connection.
The other numbers show that the total delays are dominated by
deliveries. Which Postfix delivery agent that was producing these
numbers? I suppose that was the SMTP client? If it is a local
delivery agent, then WHAT IS WRONG WITH YOUR FILE SYSTEM?
> > I suspect that your mail sending program is too slow. You can test
> > Postfix raw speed with smtp-source test program, part of the Postfix
> > source bundle.
>
> time smtp-source -4 -m 20 -S Test -l 500 -t u...@xxx.yy 127.0.0.1
> real 0m4.097s
> user 0m0.007s
> sys 0m0.017s
>
> So one thread delivers 5 mail/sec to postfix. Multiple threads scale
> well, but single thread performance seems really low.
It is consistent with the 0.21s above. Your measurement agrees with
Postfix's delays reporting.
Wietse
