From: William Lee Irwin III <wli@holomorphy.com>
To: David Lang <dlang@diginsite.com>
Cc: Till Immanuel Patzschke <tip@inw.de>,
lse-tech <lse-tech@lists.sourceforge.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: 15000+ processes -- poor performance ?!
Date: Wed, 18 Dec 2002 17:36:45 -0800 [thread overview]
Message-ID: <20021219013645.GM31800@holomorphy.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0212181717510.7848-100000@dlang.diginsite.com>
On Wed, Dec 18, 2002 at 05:20:02PM -0800, David Lang wrote:
> Ok, I wasn't sure of the cause, but I've seen this as far back as 2.2 I
> had a machine trying to run 2000 processes under 2.2 and 2.4.0 (after
> upping the 2.2 kernel limit) and top would cost me ~40% throughput on the
> machine (while claiming it was useing ~5% of the CPU)
> David Lang
It wasn't really lying to you. The issue is that the kernel samples at
regular intervals to avoid timer reprogramming overhead. Now top(1) is
isochronous in nature as it's trying to periodically refresh, and so
it runs in lockstep with the clock interrupt, and the kernel hands back
bad numbers to top(1).
Bill
next prev parent reply other threads:[~2002-12-19 1:30 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-19 0:46 15000+ processes -- poor performance ?! Till Immanuel Patzschke
2002-12-19 0:47 ` [Lse-tech] " Martin J. Bligh
2002-12-19 0:53 ` Till Immanuel Patzschke
2002-12-19 1:15 ` William Lee Irwin III
2002-12-19 1:12 ` David Lang
2002-12-19 1:25 ` William Lee Irwin III
2002-12-19 1:20 ` David Lang
2002-12-19 1:36 ` William Lee Irwin III [this message]
2002-12-19 1:42 ` Robert Love
2002-12-19 1:44 ` David Lang
2002-12-19 2:05 ` [Lse-tech] " William Lee Irwin III
2002-12-19 15:05 ` Denis Vlasenko
2002-12-19 10:27 ` William Lee Irwin III
2002-12-19 10:37 ` Alex Tomas
2002-12-19 10:55 ` William Lee Irwin III
2002-12-19 15:24 ` Martin J. Bligh
2002-12-19 15:15 ` Denis Vlasenko
2002-12-19 1:24 ` William Lee Irwin III
2002-12-19 0:59 ` Jeff Garzik
2002-12-19 1:11 ` William Lee Irwin III
2002-12-19 14:59 ` Denis Vlasenko
-- strict thread matches above, loose matches on Subject: below --
2002-12-19 1:04 Perez-Gonzalez, Inaky
2002-12-19 1:13 ` Robert Love
2002-12-19 2:31 ` Alan Cox
2002-12-19 1:58 ` Rik van Riel
2002-12-19 2:01 ` William Lee Irwin III
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