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Date:      Sun, 1 Apr 2001 13:56:22 -0500
From:      Andrew Hesford <ajh3@chmod.ath.cx>
To:        "Jason T. Luttgens" <lucky@lansters.com>
Cc:        'Mike Smith' <msmith@freebsd.org>, "'David W. Chapman Jr.'" <dwcjr@inethouston.net>, freebsd-stable@freebsd.org
Subject:   Re: Network performance question
Message-ID:  <20010401135622.A16910@cec.wustl.edu>
In-Reply-To: <000001c0badb$e4f4da70$0200010a@lucky>; from lucky@lansters.com on Sun, Apr 01, 2001 at 02:45:16PM -0400
References:  <200104011725.f31HPSC00996@mass.dis.org> <000001c0badb$e4f4da70$0200010a@lucky>

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On Sun, Apr 01, 2001 at 02:45:16PM -0400, Jason T. Luttgens wrote:
> -----Original Message-----
> From: Mike Smith [mailto:msmith@freebsd.org]
> Sent: Sunday, April 01, 2001 1:25 PM
> To: David W. Chapman Jr.
> Cc: Jason T. Luttgens; freebsd-stable@freebsd.org
> Subject: Re: Network performance question
> 
> 
> > > FreeBSD kinda disappointed me. It gets ~1000 interface errors on about
> > > 514000 packets. I switched the 3COM card out for a NetGear FA311 (sis
> > > driver). After receiving ~310000 packets, the network goes down (can't
> > > ping/telnet anywhere). At that point I have to ifconfig down and up the
> > > interface to get it back.
> 
> >You're disappointed in *FreeBSD* because of this?  These are *hardware*
> >failures you're describing here...
> 
> Hmm....so the Linux 2.4.3 kernel is somehow accessing the hardware as to not
> cause hardware failures then?

That's not it at all. Remember, FreeBSD and Linux can grab packets just
as fast as they come into the interface... the processor is many times
faster than the network card.

This is definitely a hardware issue, packets are coming too fast to
handle. I'd be willing to bet that Linux simply ignores the interface
errors, rather than reporting them.

I think what you're seeing is not that Linux handles networking better
than FreeBSD, but instead that FreeBSD is more verbose in its error
reporting. The important thing to remember here is that the card--not
the OS--determines whether or not to drop packets. Even at 100 Mbps, a
typical processor only has to poll the card 1/10 to 1/8 of the time in
order to catch every bit coming in.

I should point out that virtually every real-world networking test shows
FreeBSD outperforms comparably configured Linux.
-- 
Andrew Hesford
ajh3@chmod.ath.cx

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