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From: Joachim Breuer <jmbreuer@gmx.net>
To: Adam Goldstein <Whitewlf@Whitewlf.net>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: Very High Load, kernel 2.4.18, apache/mysql
Date: Thu, 26 Sep 2002 19:09:09 +0200	[thread overview]
Message-ID: <m3adm465l6.fsf@venus.fo.et.local> (raw)
In-Reply-To: <EFED8A1D-D02F-11D6-AD2E-000502C90EA3@Whitewlf.net> (Adam Goldstein's message of "Tue, 24 Sep 2002 22:38:56 -0400")

Adam Goldstein <Whitewlf@Whitewlf.net> writes:

> [...]
> cooperative data? Personally, I can't make heads or tails of the
> vmstat  output, and, I still have as of yet to get a -real- answer for
> what   "load" is.. besides the knee-jerk answer of "its the avg load
> over X  minutes".  :)

In the olden days (at least I learnt that definition for a system
based on 3.x BSD), the "load average" is the number of runnable
processes (i.e. those that could do work if they got a slice of CPU
time) averaged over some period of time (1, 2, 5, 10 minutes).

So, naively speaking upgrading the box to the number of CPUs indicated
by an average load average will keep it well busy while getting the
maximum amount of work done. [Yes, of course this rule of thumb does
not include the considerable overhead were one to really implement
that scheme - we used this measure when scaling hardware well before
SMP x86 became competitively available].

For Linux the load average also seems to include some notion of the
fraction of time spent waiting for disk accesses; possibly Linux
counts the number of processes which are either Runnable or Waiting
for Disk.

I don't know the concise definition in Linux's case either.


So long,
   Joe

-- 
"I use emacs, which might be thought of as a thermonuclear
 word processor."
-- Neal Stephenson, "In the beginning... was the command line"

  parent reply	other threads:[~2002-09-26 17:03 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-09-24 23:27 Adam Goldstein
2002-09-25  0:59 ` Roger Larsson
2002-09-25  1:28   ` Rik van Riel
2002-09-25  2:38     ` Adam Goldstein
2002-09-25  5:24       ` Simon Kirby
2002-09-25  6:56         ` Adam Goldstein
2002-09-25  7:20           ` Simon Kirby
2002-09-25  7:51             ` Paweł Krawczyk
2002-09-25 13:13       ` Rik van Riel
2002-09-25 22:54       ` Jose Luis Domingo Lopez
2002-09-26 17:09       ` Joachim Breuer [this message]
2002-09-26 17:16         ` Rik van Riel
2002-09-25  3:50     ` Bernd Eckenfels
2002-09-25  3:48 ` Bernd Eckenfels
     [not found] <3D90FD7B.9080209@wanadoo.fr>
2002-09-25  1:12 ` Adam Goldstein
     [not found] <0EBC45FCABFC95428EBFC3A51B368C9501AF4F@jessica.herefordshire.gov.uk>
2002-09-25 20:16 ` Adam Goldstein
2002-09-25 21:26   ` Roger Larsson
2002-09-26  3:03   ` Ernst Herzberg
2002-09-26 18:36     ` Marco Colombo
2002-09-26 19:27       ` Rik van Riel
2002-09-26 20:02         ` Marco Colombo
2002-09-26 20:09           ` Rik van Riel
2002-09-26 20:25         ` Ernst Herzberg
2002-09-27  8:52       ` Martin Brulisauer
2002-10-01  5:36   ` David Rees

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