# Re: [Condor-users] Condor preparation: monitor pool's idleness first.How?

• Date: Mon, 9 Feb 2009 13:22:42 -0500
• From: Ian Chesal <ICHESAL@xxxxxxxxxx>
• Subject: Re: [Condor-users] Condor preparation: monitor pool's idleness first.How?

> It is very difficult to estimate how often and how long the
> different PCs in the library would be idle, so that condor
> can use them.

Estimates are great because they're estimates. You can wave hands a
little and just pad it all with some margins.

Lets take the library hours as a starting point. If we know it's open 9
am -> 12 am Mon through Saturday and 12 pm -> 5 pm on Sunday. So that
means you've got guaranteed time where the machines aren't being used by
students:

9 hours from 12:00 am -> 9:00 am Tuesday, Wednesday, Thursday, Friday,
Saturday
12 hours from 12:00 am -> 12:00 pm Sunday
16 hours from 5:00 pm Sunday -> 9:00 am Monday

That's 45 + 12 + 16 = 73 hours of CPU time per core right there that you
can claim, with good argument, is available without having to do any
real world measurements.

If these machines are in the stacks, being used for stack access and
infrequent tasks, not part of the pool of machines that students sit at
to write essays and surf the web, lets make a hand waving guess that
they're idle 50% of time the library is open. I think that's probably a
pretty big understatement personally. I know what I did the stacks in my
university days and it never needed a computer...or any books for that
matter.

So now you've got an extra:

((24x7) - 73) X 0.50 = 47.5 hours of CPU time per core you can harvest

So the hand waving estimate puts you at a whopping 120.5 CPU hours per
core per week that can be grabbed. Add in stat holidays, vacation down
time, and that number creeps up a bit more.

Double check my math. I did that all pretty quick.

- Ian

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