[netperf-talk] "pace" the send rate of the UDP_STREAM

[Rick Jones]

silvia lafuente wrote:
> Hi everybody,
> I am new in netperf. I have started to use it because this other similar 
> tool "iperf" was performing very akward, so another source of 
> information is always good. Also some people have recomended me "mgen". 
> We will see...
> Anyway, my problem is that I need for my experiments to set de interval 
> between pakets and the size of the pakets and I don't understand the 
> manual when it says :
> /*<<<
> NOTE: * If you would like to "pace" the send rate of the UDP_STREAM 
> test, add a -DINTERVALS to the makefile, do a "make clean" and 
> re-compile. You can then use the -b and -w global options to set the 
> burst size (sends) and wait time (milliseconds) respectively.
>  >>>
> /Where do I have to add the -DINTERVALS option in the Makefile? I have 
> tried in CFLAGS, CPP, CPPFLAGS, DEFS ...
> Also I have generated the Makefile from the "configure" script with the 
> option --enable-intervals and -enable--spin.
> Still, the options -b and -w are not added in the man files, and I get 
> the message "Initial request burst functionality not compiled-in!" when 
> I try to use them.
> Can anybody help me?

Well, first, many bonus points to you for having read the manual!-)

Sadly, you have found a bug in the manual - it is still talking as if 
one hand-edits the Makefile whereas netperf has been converted to 
configure scripts.  I'll try to get to that at some point.

Meanwhile...

The --enable-intervals and optionally --enable-spin are indeed the right 
  things to do.  After the configure do a make clean, then a make and 
perhaps make install if you have done a previous make install.

Then, the -b and -w options become, IIRC, _global_ command-line options, 
which means they come _before_ the test-specific ones after the "--"

netperf -b <burst size> -w <wait time> etc etc etc

If you simply configure --enable-intervals, then the platform's interval 
timer will be used and the interval will be subject to the resolution of 
the platform's interval timer.

If you add --enable-spin, then netperf will "sit and spin" rather than 
use the platform's interval timer.  In this mode you should ignore any 
CPU utilization figures from netperf's -c option, althought CPU 
utilization figures from netperf's -C (remote CPU) option should be OK.

And I'll try to make the error message for the test-specific -b option 
(first burst in *RR tests) a bit clearer.

happy benchmarking,

rick jones