Re: TCP/IP send, sendfile, RAW

["Roy Rietveld" <rwm_rietveld@hotmail.com>]

Yes it is 100 MBits and there is a listener. and there are no other pc's on 
the link because its cross cable link. And when sending large buffers 
32Kbyte it will do 80 MBits. It think that there is a lot of overhead in the 
fucntion send or something.


> From: "linux-os (Dick Johnson)" <linux-os@analogic.com>
> Reply-To: "linux-os (Dick Johnson)" <linux-os@analogic.com>
> To: "Jan Engelhardt" <jengelh@linux01.gwdg.de>
> CC: "Roy Rietveld" 
> <rwm_rietveld@hotmail.com>,<linux-kernel@vger.kernel.org>
> Subject: Re: TCP/IP send, sendfile, RAW
> Date: Thu, 4 May 2006 13:56:31 -0400
>
>
> On Thu, 4 May 2006, Jan Engelhardt wrote:
>
> >> I would like to send ethernet packets with 1400 bytes payload.
> >> I wrote a small program witch sends a buffer of 1400 bytes in a endless 
> loop.
> >> The problem is that a would like 100Mbits throughtput but when i check 
> this
> >> with ethereal.
> >> I only get 40 MBits. I tried sending with an UDP socket and RAW socket. 
> I also
> >> tried sendfile.
> >> The RAW socket gives the best result till now 50 MBits throughtput.
> >
> > Limitation of Ethernet.
> >
> >
> >
> > Jan Engelhardt
>
> Maybe he can tell what he means by 100 MBits! If he is looking for
> 100 megabits per second, that's easy, That's 100/8 = 12.5 megabytes
> per second. Anything, including Windows on a wet string, will
> do that. If he is looking for 100 megabytes per second, that's
> hard. He would need 100 * 8 = 800 megabits/second. A "gigabit" link
> runs that fast if nobody else is on it, but there is a header and CRC
> tail, in addition to the payload. UDP is the protocol to use to realize
> this kind of bandwidth, but its possible for some packets to get lost and,
> if they are routed, they could even be duplicated. Also, when testing
> UDP, there must be a listener in order to realize the high speed.
> You can't just spew out a dead-end link.
>
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.6.16.4 on an i686 machine (5592.89 BogoMips).
> New book: http://www.lymanschool.com
> _
> 
>
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