From owner-freebsd-performance@FreeBSD.ORG  Mon Jun 26 21:26:19 2006
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Date: Mon, 26 Jun 2006 14:32:26 -0500
From: "Matthew D. Fuller" <fullermd@over-yonder.net>
To: Michael Vince <mv@thebeastie.org>
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Cc: freebsd-stable@freebsd.org, performance@freebsd.org,
	Nikolas Britton <nikolas.britton@gmail.com>,
	Sean Bryant <bryants@gmail.com>
Subject: Re: Gigabit ethernet very slow.
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On Mon, Jun 26, 2006 at 05:05:26PM +1000 I heard the voice of
Michael Vince, and lo! it spake thus:
> 
> According to pftop (with modulate state rules) I am able to get
> about 85megs/sec when I don't have dd running. dd does indeed eats a
> fair amount of cpu (40%) on the AMD64 6-stable machine.

dd does ridiculously small (512 byte?) read/writes, so it's gotta do a
LOT of system calls and a lot of context switching when you don't give
it a bigger blocksize.


-- 
Matthew Fuller     (MF4839)   |  fullermd@over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/
           On the Internet, nobody can hear you scream.