Re: TCP/IP send, sendfile, RAW

[Roy Rietveld]

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)" <linux-os@xxxxxxxxxxxx>
> Reply-To: "linux-os (Dick Johnson)" <linux-os@xxxxxxxxxxxx>
> To: "Roy Rietveld" <rwm_rietveld@xxxxxxxxxxx>
> CC: <linux-kernel@xxxxxxxxxxxxxxx>,<jengelh@xxxxxxxxxxxxxxx>
> 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)" <linux-os@xxxxxxxxxxxx>
> >> Reply-To: "linux-os (Dick Johnson)" <linux-os@xxxxxxxxxxxx>
> >> To: "Jan Engelhardt" <jengelh@xxxxxxxxxxxxxxx>
> >> CC: "Roy Rietveld"
> >> <rwm_rietveld@xxxxxxxxxxx>,<linux-kernel@xxxxxxxxxxxxxxx>
> >> 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
> _
> 
>
> ****************************************************************
> 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 DeliveryErrors@xxxxxxxxxxxx - and destroy all copies of 
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> Thank you.


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