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

To: bert hubert <ahu@xxxxxxx>
Subject: Re: [RESEND] tuning linux for high network performance?
From: "Richard B. Johnson" <root@xxxxxxxxxxxxxxxxxx>
Date: Wed, 23 Oct 2002 13:11:35 -0400 (EDT)
Cc: Roy Sigurd Karlsbakk <roy@xxxxxxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>, netdev@xxxxxxxxxxx, Kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
In-reply-to: <20021023170102.GA5302@xxxxxxxxxxxxxxx>
Reply-to: root@xxxxxxxxxxxxxxxxxx
Sender: netdev-bounce@xxxxxxxxxxx
On Wed, 23 Oct 2002, bert hubert wrote:

> 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? 

Ordinary DUAL Pentium 400 MHz machine does this...

Calculating CPU speed...done
Testing checksum speed...done
Testing RAM copy...done
Testing I/O port speed...done

                     CPU Clock = 400  MHz
                checksum speed = 685  Mb/s
                      RAM copy = 1549 Mb/s
                I/O port speed = 654  kb/s

This is 685 megaBYTES per second.

                checksum speed = 685  Mb/s

Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
   Bush : The Fourth Reich of America

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