[Asterisk-Users] Opinions on renice or turning off swap or ramdis

[Joe Greco]

> I have 4 gig in my * box. I'm tuning for performance and I'd like to ask
> opinions:

Bear in mind I come from a FreeBSD background.  Linux might behave
differently.

> 1. asterisk -p == renice -20 ?? 

Why?  If you have other things running on the machine, get a dedicated box
for Asterisk.  It might make sense to give it a mildly elevated priority,
but running it at -20 might cause problems if you needed to get in and
administer a runaway server.

> 2. I've turned off swap with no apparent ill effects. Can anyone commment on
> long term effects with moderate load (say, 30 SIP phones / 2-3K calls /day)

Unless Linux has a really poor swap strategy, this is a terrible idea.  Even
a mediocre swap implementation will begin swapping out lightly used pages
when memory starts getting short.  That swapping out actually *frees* memory
up, memory needed by active processes.  Turning off swap merely causes the
system to work harder, and in the event the case where a lot of unexpected 
memory is being used, you're forced to keep it all in core - probably
denying memory requests to processes that need them.  What about when
Asterisk has a really slow memory leak, growing a meg a day?  In normal
system design, while this is not desirable, it is simply swapped out to
disk, and life goes on (at least for a lot longer than the without-swap
case).

Turn on swap.  Turn on *big* swap.  Set an alarm on swap so you're notified
of any significant amount of paging.  That's the best of all worlds.

> 3. Can anyone comment on using ramdisk as swap and whether this is a good
> idea or bad idea?

RAMDISK as in something like a hardware RAMDISK?  Go ahead, but you're
throwing away money.  Figuring out why a system with 4GB of memory and is
only running Asterisk is swapping is a cheaper fix.

A software RAMDISK?  No way.  You're eating up system RAM to provide for
the lack of ... system RAM.  Not smart.

> I'm using 2.6 kernel. I've modified the PCI latency in rc.local:
> 
> setpci -v -s <my T100P address> latency_timer=ff
> 
> Anyone else have any performance tips?

Carefully profile your system to find out where the bottlenecks really are.
Then get out the Attitude Adjuster (BOFH's find that it works nearly as well
on systems as it does on people).  Then go buy a system with none of those
bottlenecks.  ;-)

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.