[Dovecot] POP3 Dovecot Auth CPU usage 75%+

[Root Kev]

I tried making the changes that you suggested but it didn't seem to make a
noticeable difference. It should be using the shadow file directly.  The
shadow file has the default Ubuntu system accounts and 16 user accounts, so
overall fairly small.  The nsswitch.conf file is set as default:
# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.

passwd:         compat
group:          compat
shadow:         compat

hosts:          files dns
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis

An example of users connecting and the Auth process using alot of CPU (from
top):

Cpu(s): 87.4%us,  8.0%sy,  0.0%ni,  2.3%id,  0.0%wa,  0.7%hi,  1.7%si,
0.0%st
Mem:   1026096k total,   533924k used,   492172k free,    60340k buffers
Swap:  1757176k total,        0k used,  1757176k free,   414212k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+
COMMAND

  643 dovecot   20   0  3096 1616 1208 S 50.7  0.2   0:01.76
auth

  644 root      20   0  3096 1524 1140 S  1.3  0.1   0:00.08
auth

  642 dovenull  20   0  4276 1612 1256 S  1.0  0.2   0:00.03
pop3-login

  623 root      20   0  2704 1020  772 S  0.7  0.1   0:00.02
dovecot

  627 root      20   0  4344 2808 1056 S  0.7  0.3   0:00.03
config

  631 syslog    20   0 33916 1924 1036 S  0.3  0.2   0:01.61
rsyslogd

  696 serverma  20   0  5464 2564 2040 R  0.3  0.2   0:00.01
pop3

    1 root      20   0  2652 1604 1216 S  0.0  0.2   0:01.59
init

    2 root      20   0     0    0    0 S  0.0  0.0   0:00.00
kthreadd

Thanks for any other ideas....

Kevin

On Fri, Apr 13, 2012 at 7:55 AM, Timo Sirainen <tss at iki.fi> wrote:

> On 12.4.2012, at 23.46, Root Kev wrote:
>
> So is it the "auth" process or "auth worker" process? What if you add:
>
> > passdb {
> >  driver = shadow
> > }
> > userdb {
> >  driver = passwd
> args = blocking=yes
> > }
>
> does that move the CPU usage from "auth" to "auth worker" process? Is it
> using /etc/shadow and /etc/passwd files? Are they large? Do you have
> enabled other weird stuff in /etc/nsswitch.conf (and were there some other
> files related to them as well?)
>
>