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Re: timing results

To: Guilhem Tardy <guilhem_tardy@xxxxxxxxx>
Subject: Re: timing results
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Mon, 01 Oct 2001 07:59:18 -0700
Cc: netdev@xxxxxxxxxxx
Organization: Candela Technologies
References: <20010926214925.7742.qmail@xxxxxxxxxxxxxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
Guilhem Tardy wrote:
> 
> > Hrm, my tests, where I use mili-second timers in data sent
> > from userspace shows that I can run 100Mbps of TCP, UDP,
> > and custom Ethernet traffic with less than 1 milisecond of
> > latency.  And that is end-to-end (user-space to user-space).
> > This is 100Mbps tx and 100Mbps rx at the same time, too...
> >
> > Maybe you don't mean miliseconds??
> >
> > ping also shows about .3ms for round-trip on normal fast-ethernet
> > and modern computers....
> >
> > Ben
> 
> I run over a 100Mbps ethernet card from 3COM (hence the 3c59x.c driver), and
> stand by my measurements in microseconds. Yeah, you're right this was
> microseconds (sorry for the heart attack ;). Really, this can go as low as 19
> usec and as high as 1300+ usec for the total.
> 
> I included the application that receives and sinks the UDP traffic for your
> consideration. One thing puzzles me: my calibration results in either 350 or
> 800 megaticks per second, changing from time to time on the same setup. Would
> you think of an explanation for that?

Maybe your CPU clocks itself down when over-heated?  (Is your cooling
adequate?)  I have no other ideas as to why the timing changes..

Ben

> 
> Guilhem.
> 
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>   
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>                                Name: measure_udp_traffic.c
>    measure_udp_traffic.c       Type: application/x-unknown
>                            Encoding: base64
>                         Description: measure_udp_traffic.c

-- 
Ben Greear <greearb@xxxxxxxxxxxxxxx>          <Ben_Greear@xxxxxxxxxx>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear

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