Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!know!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!apple!well!jef
From: jef@well.sf.ca.us (Jef Poskanzer)
Newsgroups: comp.windows.x
Subject: Re: What does xload measure ??  (sunclock)
Message-ID: <21008@well.sf.ca.us>
Date: 5 Oct 90 20:11:57 GMT
References: <9010050913.AA02121@lightning.McRCIM.McGill.EDU>
Reply-To: Jef Poskanzer <jef@well.sf.ca.us>
Organization: Paratheo-Anametamystikhood Of Eris Esoteric, Ada Lovelace Cabal
Lines: 35

In the referenced message, mouse@LIGHTNING.MCRCIM.MCGILL.EDU wrote:
}> Moral: dump xload in the toilet.  Use xcpu or xmeter or something
}> like them instead.
}
}What are xcpu and/or xmeter, and how do they avoid the sort of problems
}under discussion?

xmeter was posted to comp.sources.x a week ago, v9i59.  It's a generalization
of xload to handle any statistic that can be rstatted, including non-idle
cpu percentage, which is what you want to measure to get a load estimate.
Cpu percentage doesn't suffer from the syncronization/beating problems
discussed, because it is a direct measure, not sampled.

xcpu is a program that has been kicking around since X10, originator
unknown.  It graphs cpu percentage, and is otherwise just like xload.
Craig Leres and I posted a version for X11R2 I believe, and he has been
working on an up to date version.

The only quibble I have with cpu percentage meters is that they don't
differentiate between niced and normal percentage, so if you have a
niced background process computing mandelbrots or guessing passwords or
something, your cpu meter becomes useless.  The right way to fix this
is to graph the niced and normal percentages on top of each other, but
I don't think the StripChart widget lets you do that.

By the way, my opinion of the run queue length measure is that it dates
from the dark ages of huge timesharing systems, when the assumption was
that the cpu would never be idle.  It's not so much a measure of load
as of *overload*.  But modern workstations don't get overloaded in the
cpu area, they are more likely to be I/O-limited.
---
Jef

  Jef Poskanzer  jef@well.sf.ca.us  {ucbvax, apple, hplabs}!well!jef
            ...lucky for me morning only comes once a day.