Re: Transfer vs. Bandwidth


* Stephen Hemminger <shemminger --at-- osdl.org> [Nov 16, 2004 at 03:49:14PM MST]:
> On Tue, 16 Nov 2004 16:02:54 -0500
> Jason Hammerschmidt <JHammerschmidt --at-- metroland.com> wrote:
> > ...
> > iperf -c 172.16.155.74
> > ------------------------------------------------------------
> > Client connecting to 172.16.155.74, TCP port 5001
> > TCP window size: 65.0 KByte (default)
> > ----------------------------------------------------
> > [  3] local 10.150.0.89 port 50722 connected with 172.16.155.74 port 5001
> > [ ID] Interval       Transfer     Bandwidth
> > [  3]  0.0-10.0 sec  96.0 MBytes  80.4 Mbits/sec
> 
> The confusion arises because iperf is following the common usage and
> converting the definition of "mega" when going from measurement of
> storage to communication.
> 
> MBytes for space are measured Mega  = 1024*1024
> rates are measured with mega = 1000000
> 
> 8 * 96 * 1024 * 1024 = 805306368 bits
> 
> http://en.wikipedia.org/wiki/Megabyte

Shouldn't you be using the SI prefixes for binary multiples in this
case...  Mi = 2^(20), etc.

[ ID] Interval       Transfer      Bandwidth
[  3]  0.0-10.0 sec  96.0 MiBytes  80.4 Mbits/sec
                          ^^

See http://physics.nist.gov/cuu/Units/binary.html

Using this standard might help clear up this confusion.

-Matt

-- 
Matthew Bohnsack              http://bohnsack.com/
Email: <mpbohns --at-- sandia.gov>   Phone: 505.844.9162
Sandia National Laboratories  



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