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
I get ~100uS wehen pinging with raw ethernet frames.
PS: Intel 82557 Ethernet Pro 100 NIC's
TJ
ons, 2002-01-30 kl. 17:47 skrev Richard B. Johnson:
> On Wed, 30 Jan 2002, Zwane Mwaikambo wrote:
>
> > On Wed, 30 Jan 2002, Richard B. Johnson wrote:
> >
> > > But it's already connected.
> > >
> > >
> > > host:
> > > for (;;) {
> > > gettimeofday(...);
> > > write(s, buf, 64);
> > > read(s, buf, sizeof(buffer));
> > > gettimeofday(...);
> > > /* delay is 1.0 ms */
> > > }
> > > server is IPPORT_ECHO
> >
> > You didn't make that explicit in your previous email, and anyway what kind
> > of resolution can you expect from gettimeofday...
> >
>
> The resolution is in microseconds. That's the specification. Not
> all 'codes' are exercised of course, but the resolution is sufficient
> to discern a 10 to 30 microsecond difference. I'm trying to measure
> milliseconds, well within its capability. FYI, this is what `ping`
> and `traceroute` use. It's fine.
>
>
> 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.
>
>
> -
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-- _________________________________________________________________________Terje Eggestad mailto:terje.eggestad@scali.no Scali Scalable Linux Systems http://www.scali.com
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