From: Greg Ercolano <erco@(email surpressed)>
Subject: Re: Temporarily limit max # of CPUs on a host
   Date: Mon, 11 Feb 2008 06:05:37 -0500
Msg# 1679
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Marco Recuay wrote:
> We just got a few 8-core workstations, and I was thinking that it would 
> be nice to be able to online only some of the cores, allowing artists 
> to work with half, and rush to utilize the other half at times when 
> full threading isnt needed.

	There's a couple of ways.

	RUSH -RESERVE
	-------------

	You can use 'rush -reserve' from the command line to reserve
	processors at a particular priority. For instance, if you're
	on machine "tahoe" and want to reserve 2 processors at 500 priority:

		rush -reserve tahoe=2@999

	This creates a "RESERVE" job that you can manage just like
	a normal job; dump it when you want to get rid of the reservation.
	For more info and examples see:
	http://www.seriss.com/rush-current/rush/rush-command-line-options.html#-reserve

	There is currently no GUI way to create a reserve job, it
	must be done from the command line.

	RUSH HOSTS FILE
	---------------
	You can enable/disable processors in rush in a more permanent
	way by modifying the CPUS column in the rush/etc/hosts file.

	For instance if machine "tahoe" has 8 processors, but you only
	want 4 to be available to rush, you can set the CPUS column
	in the rush/etc/hosts file to '4'. You can use 'rushadmin'
	to do this easily:

		1) Run rushadmin
		2) Click on 'hosts'
		3) Change the CPUS column for the machine in question
		4) Hit 'Save'
		5) Hit 'Send'

> I thought maybe it would be possible for the 8-core user to submit a 
> "dummy" job to their own machine, which would grab a certain number of 
> cores without doing any real processing, but I'm sure that I'm 
> underestimating what is needed to do this.

	This is exactly what 'rush -reserve' does, running commands
	that are essentially 'sleep' commands that do nothing, and just
	take up slots in rush.

	If you wanted to make your own 'reserve' job, you can
	'roll your own', for example the almost-equivalent of
	'rush -reserve tahoe=2@500' would be:

rush -submit tahoe << EOF
title   RESERVE
frames  1-10
cpus    tahoe=2@500
command rush -sleep -1
EOF

	..which kicks off a job that runs 'rush -sleep -1', which
	just does a 'sleep forever'.

	Note that the only way another job can usurp this reservation
	is for the job to ask for this machine with a killer priority
	that is higher than 500. (eg. "tahoe=2@501k")

-- 
Greg Ercolano, erco@(email surpressed)
Seriss Corporation
Rush Render Queue, http://seriss.com/rush/
Tel: (Tel# suppressed)
Fax: (Tel# suppressed)
Cel: (Tel# suppressed)

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