From: "linux-os (Dick Johnson)" <[email protected]>
Reply-To: "linux-os (Dick Johnson)" <[email protected]>
To: "Roy Rietveld" <[email protected]>
CC: <[email protected]>,<[email protected]>
Subject: Re: TCP/IP send, sendfile, RAW
Date: Thu, 4 May 2006 14:27:47 -0400
On Thu, 4 May 2006, Roy Rietveld wrote:
> 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.
>
Use sendto() and recvfrom() for UDP. Stream protocols require an ACK and
are slower.
>
>> From: "linux-os (Dick Johnson)" <[email protected]>
>> Reply-To: "linux-os (Dick Johnson)" <[email protected]>
>> To: "Jan Engelhardt" <[email protected]>
>> CC: "Roy Rietveld"
>> <[email protected]>,<[email protected]>
>> 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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>
>
>
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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