[72965] in North American Network Operators' Group
Re: Quick question.
daemon@ATHENA.MIT.EDU (Paul G)
Wed Aug 4 02:59:07 2004
From: "Paul G" <paul@rusko.us>
To: <nanog@merit.edu>
Date: Wed, 4 Aug 2004 02:54:06 -0400
Errors-To: owner-nanog-outgoing@merit.edu
----- Original Message -----
From: "Paul Jakma" <paul@clubi.ie>
To: "Alexei Roudnev" <alex@relcom.net>
Cc: "Michel Py" <michel@arneill-py.sacramento.ca.us>; "Nanog"
<nanog@nanog.org>
Sent: Wednesday, August 04, 2004 2:39 AM
Subject: Re: Quick question.
--- snip ---
> Not really.. this is a resource exhaustion problem, and you can not
> cure this, given buggy apps, by throwing more CPUs at it.
>
> Let's say you have some multi-process or multi-threaded application
> which regularly spawns/forks new processes/threads, but it is buggy
> and prone to having individual processes/threads spin.
>
> So one spins, but you still have plenty of CPU time left cause you
> have two CPUs. Another spins, and the machine starts to crawl. So you
> solve this problem by upgrading to a quad-SMP machine. And guess what
> happens? :)
the second cpu buys you time - it is unlikely you're going to be able to
react in time on a busy single cpu box with a runaway process (it launches
into a death sprial almost immediately), but you would usually have 10-15
mins on a dual cpu box at a minimum or maybe infinity if you enforce cpu
affinity for apps that tend to misbehave.
paul
