How does your syslog config look like ?
Did you prefix the filename with the magic - symbol in order to ask for async
I/Os on that file?
E.g.
*.info;mail.none;authpriv.none;cron.none
-/var/log/messages
mail.*
-/var/log/maillog
local4.*
-/var/log/slapd.log
Instead of
*.info;mail.none;authpriv.none;cron.none
/var/log/messages
mail.* /var/log/maillog
local4.*
/var/log/slapd.log
++Cyrille
Man syslog.conf
Regular File
Typically messages are logged to real files. The file has to be
specified with full
pathname, beginning with a slash ??/??.
You may prefix each entry with the minus ??-?? sign to omit syncing the
file after every
logging. Note that you might lose information if the system
crashes right behind a
write attempt. Nevertheless this might give you back some performance,
especially if
you run programs that use logging in a very verbose manner.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Berend De Schouwer
Sent: Wednesday, June 13, 2012 12:28 PM
To: [email protected]
Subject: loglevel expected performance impact
I'm running some 2.4.23 servers, and I've encountered some slowdown on loglevel
other than 0. Even 256 (stats; recommended) impacts about a 4x slowdown on
queries. Logging is to syslog.
Running ldapsearch slows from 0.005-0.010 seconds to about 0.030-0.040 seconds;
and that includes loading the binary. That's from localhost to remove
potential DNS lookups.
I stumbled across this when logging was wrong, and the slowdown was 100x.
I'm aware that 2.4.23 isn't the latest version. I'm also quite happy, for now,
to run loglevel 0.
I'm wondering if this is the expected behaviour, given that it's the
recommended configuration. Or should I go dig to find the slowdown?
(I did check the indexes, and db_stats, etc. All seems fine.)
I apologise for the disclaimer,
Berend
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