[Dovecot] How to debug slow operation

[zbigniew szalbot]

Hello,

zbigniew szalbot pisze:
> Hello,
>
> I am no programmer at all. I have dovecot set up on two very similar 
> machines. On one of the boxes, the dovecot server has recently been 
> showing slower response times. It feels slower. Where it is slower, 
> dovecot works as an auth server for postfix. I have replaced exim with 
> postfix on that box and I think since then dovecot started to slow down. 
> On the other machine the MTA is exim.
>
> I'd like to ask how to go about debugging the problem. Neither machine 
> serves many users, the one that is slower has currently only two. It's a 
> home setup really.
>
> Here's the output of dovecot -n
>
> # 1.0.5: /usr/local/etc/dovecot.conf
> protocols: imap imaps pop3 pop3s
> disable_plaintext_auth: no
> login_dir: /var/run/dovecot/login
> login_executable(default): /usr/local/libexec/dovecot/imap-login
> login_executable(imap): /usr/local/libexec/dovecot/imap-login
> login_executable(pop3): /usr/local/libexec/dovecot/pop3-login
> login_greeting: Server ready.
> verbose_proctitle: yes
> first_valid_uid: 125
> first_valid_gid: 125
> mail_extra_groups: mail
> mail_location: maildir:/usr/local/virtual/%d/%n
> mail_executable(default): /usr/local/libexec/dovecot/imap
> mail_executable(imap): /usr/local/libexec/dovecot/imap
> mail_executable(pop3): /usr/local/libexec/dovecot/pop3
> mail_plugins(default): quota imap_quota
> mail_plugins(imap): quota imap_quota
> mail_plugins(pop3): quota
> mail_plugin_dir(default): /usr/local/lib/dovecot/imap
> mail_plugin_dir(imap): /usr/local/lib/dovecot/imap
> mail_plugin_dir(pop3): /usr/local/lib/dovecot/pop3
> imap_client_workarounds(default): delay-newmail outlook-idle 
> netscape-eoh tb-extra-mailbox-sep
> imap_client_workarounds(imap): delay-newmail outlook-idle netscape-eoh 
> tb-extra-mailbox-sep
> imap_client_workarounds(pop3): outlook-idle
> pop3_uidl_format(default):
> pop3_uidl_format(imap):
> pop3_uidl_format(pop3): %08Xu%08Xv
> pop3_client_workarounds(default):
> pop3_client_workarounds(imap):
> pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
> auth default:
>   mechanisms: plain login
>   passdb:
>     driver: sql
>     args: /usr/local/etc/dovecot-postfix-sql.conf
>   userdb:
>     driver: sql
>     args: /usr/local/etc/dovecot-postfix-sql.conf
>   socket:
>     type: listen
>     client:
>       path: /var/spool/postfix/private/auth
>       mode: 384
>       user: postfix
>       group: postfix
>
> Many thanks for your suggestions!
>
> Zbigniew Szalbot
>
>   

I now have the dump as explained on page 
http://wiki.dovecot.org/Debugging/ProcessTracing
After a one minute operation the file is 8,5MB big. I did run kdump -T 
-f log on it but I have no knowledge to interpret its content. Can 
anyone help? Thanks!

Zbigniew Szalbot