Subject: Re: To renice, or not to renice...
To: Michael W. Lucas <mwlucas@blackhelicopters.org>
From: Andy R <quadreverb@yahoo.com>
List: netbsd-help
Date: 03/05/2004 15:16:27
--- "Michael W. Lucas" <mwlucas@blackhelicopters.org>
wrote:
> On Fri, Mar 05, 2004 at 05:26:37PM -0500, Timothy A.
> Musson wrote:
> > At 04:26 PM 3/5/04 , David Howland wrote:
> > >I use NetBSD at home as a NAT/Firewall/utility
> machine, running between my
> > 
> > >It runs great, no problems, except every 5
> minutes on the dot, there is a
> > >big spike of lag in game for all connected
> clients.  Obviously, this is
> > >related to perl starting from cron to run MRTG. 
> I would rather quake3 get
> > 
> > I haven't deployed MRTG, but it seems there should
> be a way to have the
> > module or whatever is being run stay resident in
> memory. Or, you could turn
> > off MRTG ;)
> 
> Wow, something I can speak quite authoritatively
> about!
> 
> I just switched MRTG from the five-minute cron job
> mode to daemon mode
> with the RRDTool backend.  This was on a P533 that
> took 4.8 minutes to
> complete a full run on my hundreds of MRTG targets.
> 
> System load dropped from a pretty continuous 16 down
> to 0.16.
> 
> It's not hard to do, just use the RunAsDaemon config
> option and
> install rrdtool, then use any of the varies
> mrtg/rrdtool front ends.
> I use 14all.cgi.
> 
> Pretty extensive documentation on how to do this at
> www.mrtg.org.
> 
> The CGIs might seem slow, but if you install
> mod_perl they fly and
> take up even less resources.
> 
> ==ml
> 
> -- 
> Michael Lucas		mwlucas@FreeBSD.org,
> mwlucas@BlackHelicopters.org
> 
> Today's chance of throwing it all away to start a
> goat farm: 44.3%
> 		http://www.BlackHelicopters.org/~mwlucas/

Wow, we have a famous dude among us!

I read both your books, great books. I still pour over
stuff I've already read to make sure it stays in
there... Please write more books on BSD! I will buy
them!

I don't know much about MRTG, but I did install it and
it looks cool. One of these days I'll actually make it
work.

On renice, generally it's best to reduce the nice
number on something (ie lower it's priority). You
don't want some rogue program (such as a game server,
that's as rogue as it gets!) taking more CPU than
otherwise useful programs your system needs to stay
running. Rather, find the things that are taking
priority from things you really want to not be
interrupted, and reduce their priority. MRTG doesn't
seem like a hugely important thing to get all the CPU
it needs when it needs it.

Renicing to a lower priority doesn't always mean that
something isn't going to slow down your system though.
If it needs I/O or access to some other pipe that is
slow or near capacity, you're still going to get a
slowdown.

Andy

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