Re: Quick question.

["Paul G" <paul () rusko us>]

----- 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