[Simh] VAX: CPU Usage and Network Timeout

[Ethan Dicks]

On Wed, Jun 08, 2005 at 10:12:14AM -1000, Tim Newsham wrote:
> Why would you want your machine to use less than 100% of its cpu?
> I mean, you paid for the whole cpu, might as well use it.

Heat.

In principle, there should be no reason to not use CPU capacity that's paid for.  In practice, modern machines run the emulation so fast that one doesn't need to run the app at full bore to get an acceptable experience.

I used to have an app running on my home desktop machine that would display a running graph of the temp of its CPU.  When I would take a break and run something like Quake (this was a while ago), on exiting the session, I could see a thermal record of my gaming time; it was several degrees higher than when the machine was just sitting around waiting for me to wiggle the mouse and click on browser tags.  In the summer (since I have no AC at home), I would sometimes have to shut the machine down because even with extra fans, 90F air doesn't do a good job of keeping a 1GHz machine cool when it's near its shutdown temps.

If there are no thermal issues, then the only other issue would be time for other processes.  As you point out, 'nice' is your friend.

-ethan

-- 
Ethan Dicks                           Ethan.Dicks at icecube.wisc.edu
AMANDA/IceCube                   
University of Wisconsin-Madison

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