[Dovecot] Login process connection routing

2010-07-20 Thread Brandon Davidson 
Timo,

Just out of curiosity, how are incoming connections routed to login
processes when run with:
service imap-login { service_count = 0 }

I've been playing with this on our test director, and the process connection
counts look somewhat unbalanced. I'm wondering if there are any performance
issues with having a single process handle so many connections. It seems
fine (system load is actually lower than with service_count = 1), but I
thought I'd ask.

/usr/sbin/dovecot
 \_ dovecot/imap-login
 \_ dovecot/imap-login [1 connections (1 TLS)]
 \_ dovecot/imap-login
 \_ dovecot/imap-login [5 connections (5 TLS)]
 \_ dovecot/imap-login [1 connections (1 TLS)]
 \_ dovecot/imap-login [4 connections (4 TLS)]
 \_ dovecot/imap-login [1 connections (1 TLS)]
 \_ dovecot/imap-login [1 connections (1 TLS)]
 \_ dovecot/imap-login [315 connections (315 TLS)]
 \_ dovecot/imap-login [63 connections (63 TLS)]
 \_ dovecot/imap-login [12 connections (12 TLS)]
 \_ dovecot/imap-login
 \_ dovecot/imap-login [10 connections (10 TLS)]
 \_ dovecot/imap-login [2 connections (2 TLS)]
 \_ dovecot/imap-login [370 connections (370 TLS)]
 \_ dovecot/imap-login [24 connections (24 TLS)]

-Brad

Re: [Dovecot] Login process connection routing

2010-07-20 Thread Timo Sirainen 
On Tue, 2010-07-20 at 09:57 -0700, Brandon Davidson wrote:
 Timo,
 
 Just out of curiosity, how are incoming connections routed to login
 processes when run with:
 service imap-login { service_count = 0 }
 
 I've been playing with this on our test director, and the process connection
 counts look somewhat unbalanced. I'm wondering if there are any performance
 issues with having a single process handle so many connections. It seems
 fine (system load is actually lower than with service_count = 1), but I
 thought I'd ask.

Dovecot lets kernel assign it. Whichever process grabs it first, handles
it.

 /usr/sbin/dovecot
  \_ dovecot/imap-login
  \_ dovecot/imap-login [1 connections (1 TLS)]
  \_ dovecot/imap-login
  \_ dovecot/imap-login [5 connections (5 TLS)]
  \_ dovecot/imap-login [1 connections (1 TLS)]
  \_ dovecot/imap-login [4 connections (4 TLS)]
  \_ dovecot/imap-login [1 connections (1 TLS)]
  \_ dovecot/imap-login [1 connections (1 TLS)]
  \_ dovecot/imap-login [315 connections (315 TLS)]
  \_ dovecot/imap-login [63 connections (63 TLS)]
  \_ dovecot/imap-login [12 connections (12 TLS)]
  \_ dovecot/imap-login
  \_ dovecot/imap-login [10 connections (10 TLS)]
  \_ dovecot/imap-login [2 connections (2 TLS)]
  \_ dovecot/imap-login [370 connections (370 TLS)]
  \_ dovecot/imap-login [24 connections (24 TLS)]

You probably have too many login processes. process_min_avail should be
set to about the same as the number of CPU cores. Since there are two
processes handling most of the connections, do you also happen to have 2
cores? :)

Re: [Dovecot] Login process connection routing

2010-07-20 Thread Brad Davidson 
Timo,

 -Original Message-
 From: Timo Sirainen [mailto:t...@iki.fi]
 
 Dovecot lets kernel assign it. Whichever process grabs it first, handles
 it.

Makes sense.

 You probably have too many login processes. process_min_avail should be
 set to about the same as the number of CPU cores.

Ahh, OK - that's good guidance, I didn't remember hearing that. I had just left 
the old setting in place from when we were forking off a process per session, 
where it made sense as more of a prefork.

 Since there are two
 processes handling most of the connections, do you also happen to have 2
 cores? :)

Two cores with HT (looks like four), but yes ;)

Thanks!

-Brad