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SubjectRe: TCP/IP Speed
From
Date
tor, 2002-01-31 kl. 16:26 skrev Richard B. Johnson:
> On 31 Jan 2002, Terje Eggestad wrote:
>
> > Hmmm,
> >
> > I tend to use the rdtsc register to do these kind of measurements,
> > but I get ~110 uS round trip with or without TCP_NDELAY
> >
>
> AMD-SC520 ( 'i486 ) don't have such an instruction. Therefore benchmarks,
> which have to run 'everywhere' need to be generic.
>

too bad...

> > I get ~100uS wehen pinging with raw ethernet frames.
>
> >
> > PS: Intel 82557 Ethernet Pro 100 NIC's
> >
>
> Ping doesn't count. ICMP is handled in the kernel a few procedures
> removed from actual frame acquisition. It looks like the kernel
> takes the data I'm waiting for, hides it away for awhile, scheduling
> other tasks, then finally decides to wake me up, having been sleeping
> in read() for a whole millisecond. This is entirely unacceptable.
>

Actually, my "ping" is even less than icmp. I open the ethX with family
= AF_PACKET, and provide the full 802 frame.

> Since this 1000 data-buffers-per-second limitation is independent of
> CPU speed and/or RAM speed, it seems to be imposed artificially by
> the network implementation. It may have something to do with additions
> to stop DOS or whatever. I need to turn it OFF.
>

Hmmm, guess I haven't tried abutally sending 1000 writes.
If you send my you test program, I could try it on my HW's tomorrow.


> I have done setsockopt(s, IPPROTO_TCP, TCP_NODELAY, &x sizeof(x));
> ... SOL_TCP, TCP_NODELAY...
> with int x = 1;, everywhere a socket is created. It seems like a
> no-op.
>
> My sun uses SunOS 5.5.1, with GNU 'C' runtime libraries, gcc 2.7.2, and
> it doesn't display this problem. The speed is lower because it has only
> a 10-base network connection, but the Tx/Rx time is running around
> 250 to 300 microseconds, not the awful 1 millisecond.
>
>
> Cheers,
> Dick Johnson
>
> Penguin : Linux version 2.4.1 on an i686 machine (797.90 BogoMips).
>
> I was going to compile a list of innovations that could be
> attributed to Microsoft. Once I realized that Ctrl-Alt-Del
> was handled in the BIOS, I found that there aren't any.
>
--
_________________________________________________________________________

Terje Eggestad mailto:terje.eggestad@scali.no
Scali Scalable Linux Systems http://www.scali.com

Olaf Helsets Vei 6 tel: +47 22 62 89 61 (OFFICE)
P.O.Box 150, Oppsal +47 975 31 574 (MOBILE)
N-0619 Oslo fax: +47 22 62 89 51
NORWAY
_________________________________________________________________________

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