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 15:12:34 -0400
On Thu, 4 May 2006, Roy Rietveld wrote:
> 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.
>
That's probably the granuarity of gettimeofday().
You need to do something like:
#define USEC 1e6
double start_time, end_time, total_time, bytes_per_second;
get_timeofday(&tb);
start_time_usec = ((double)tb.tv_sec * USEC) +
(double)tb.tv_usec;
for(i= 0; i <1000; i++)
sendto(s, buf, buf_size,...);
get_timeofday(&tb);
end_time_usec = ((double)tb.tv_sec * USEC) + (double)tb.tv_usec;
total_time = (end_time_usec - start_time_usec) / USEC;
bytes_per_second = (buf_size * 1000) / total_time;
>
>> 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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>>>> privileged. Any review, retransmission, dissemination, or other use
of
>>>> this information by persons or entities other than the intended
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>>>> 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
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>>>> Thank you.
>>>> -
>>>> To unsubscribe from this list: send the line "unsubscribe
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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
>> _
>>
>>
>> ****************************************************************
>> 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
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disclosing
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>> Thank you.
>
>
> -
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in
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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
_
****************************************************************
The information transmitted in this message is confidential and may be
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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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