[rsyslog] $OptimizeForUniprocessor missing from 3.22.0 source?

[david at lang.hm]

On Thu, 28 May 2009, Howard Wilkinson wrote:

> Rainer Gerhards wrote:
>>> -----Original Message-----
>>> From: rsyslog-bounces at lists.adiscon.com [mailto:rsyslog-
>>> bounces at lists.adiscon.com] On Behalf Of Howard Wilkinson
>>> 
>>> I have recently installed the 3.22.0 release and found that the
>>> $OptimizeForUniprocessor configuration facility is missing from the
>>> source, is this intentional?
>>> 
>> 
>> Well... not intentional, but simply not present in v3. This is a v4 
>> feature.
>> 
>> Rainer
>>
>> 
> In that case can someone tell me what I am doing wrong with this 
> configuration.
>
> I have 3.22.0 installed on all systems in the network! I have 2 receiving 
> servers (1 master and one backup) that are contacted via RELP, falling back 
> to TCP and then UDP if things go wrong. On the receiving servers I log 
> everything into a replicated MySQL database. This all functions... but the 
> master server gets further and further behind with the log messages until 
> things on client boxes start hanging. The logging servers run the MYSQL DB 
> engines but are only about 25% CPU loaded (load level is 2.1 ish). The 
> database is stored on a SCSI mirror (U160) and there does not seem to be any 
> IO overload. So what is going on? Config attached!

can you tell how many inserts/sec you are getting on your MySQL database? 
what table type are you using? do you have a battery-backed write cache on 
your SCSI controller?

I suspect that your problem is that the database just isn't keeping up 
with the inbound data rate, so things queue up until the queue is full, 
then things start queueing on the clients.

the only way to fix this is to increase the speed of writing to the 
database. options may include

1. tuning MySQL for higher insert rates (possibly including disabling 
fsync)

2. improving the disk systems to handle more transactions/sec (enabling a 
disk cache will do wonders)

3. increase the number of worker threads so that rsyslog can have multiple 
inserts in flight at the same time

4. moving to rsyslog 4 which includes the ability to insert multiple 
records in one transaction

David Lang
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