Re: TCP/IP send, sendfile, RAW

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i tried but it doesn't help, still 40MBits. Does send or sento cost a lot of cpu load.

i tried to measure the cpu time sendto cost.

gettimeofday(start)
sendto
gettimeofday(end)

print end - start

time measured is 250 us.


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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>> Analogic Corporation immediately - by replying to this message or by
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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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The information transmitted in this message is confidential and may be privileged. Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited. If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to [email protected] - and destroy all copies of this information, including any attachments, without reading or disclosing them.

Thank you.


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