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Re: [RESEND] tuning linux for high network performance?

To: Roy Sigurd Karlsbakk <roy@xxxxxxxxxxxxx>
Subject: Re: [RESEND] tuning linux for high network performance?
From: bert hubert <ahu@xxxxxxx>
Date: Wed, 23 Oct 2002 19:01:02 +0200
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>, netdev@xxxxxxxxxxx, Kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
In-reply-to: <200210231542.48673.roy@karlsbakk.net>
Mail-followup-to: bert hubert <ahu@xxxxxxx>, Roy Sigurd Karlsbakk <roy@xxxxxxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>, netdev@xxxxxxxxxxx, Kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
References: <200210231218.18733.roy@karlsbakk.net> <20021023130101.GA646@outpost.ds9a.nl> <1035379308.5950.3.camel@rth.ninka.net> <200210231542.48673.roy@karlsbakk.net>
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On Wed, Oct 23, 2002 at 03:42:48PM +0200, Roy Sigurd Karlsbakk wrote:
> > The e1000 can very well do hardware checksumming on transmit.
> >
> > The missing piece of the puzzle is that his application is not
> > using sendfile(), without which no transmit checksum offload
> > can take place.
> 
> As far as I've understood, sendfile() won't do much good with large files. Is 
> this right?

I still refuse to believe that a 1.8GHz Pentium4 can only checksum
250megabits/second. MD Raid5 does better and they probably don't use a
checksum as braindead as that used by TCP.

If the checksumming is not the problem, the copying is, which would be a
weakness of your hardware. The function profiled does both the copying and
the checksumming.

But 250megabits/second also seems low.

Dave? 

Regards,

bert

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