On Tue, Jan 18, 2011 at 11:41:22AM -0800, Rick Jones wrote:

quoted

So it won't be all that simple to implement well, and before we try,
I'd like to know whether there are applications that are helped
by it. For example, we could try to measure latency at various
pps and see whether the backpressure helps. netperf has -b, -w
flags which might help these measurements.

Those options are enabled when one adds --enable-burst to the
pre-compilation ./configure  of netperf (one doesn't have to
recompile netserver).  However, if one is also looking at latency
statistics via the -j option in the top-of-trunk, or simply at the
histogram with --enable-histogram on the ./configure and a verbosity
level of 2 (global -v 2) then one wants the very top of trunk
netperf from:

http://www.netperf.org/svn/netperf2/trunk

to get the recently added support for accurate (netperf level) RTT
measuremnts on burst-mode request/response tests.

happy benchmarking,

rick jones

PS - the enhanced latency statistics from -j are only available in
the "omni" version of the TCP_RR test.  To get that add a
--enable-omni to the ./configure - and in this case both netperf and
netserver have to be recompiled.

Is this TCP only? I would love to get latency data from UDP as well.

 For very basic output one can
peruse the output of:

src/netperf -t omni -- -O /?

and then pick those outputs of interest and put them into an output
selection file which one then passes to either (test-specific) -o,
-O or -k to get CVS, "Human" or keyval output respectively.  E.G.

raj@tardy:~/netperf2_trunk$ cat foo
THROUGHPUT,THROUGHPUT_UNITS
RT_LATENCY,MIN_LATENCY,MEAN_LATENCY,MAX_LATENCY
P50_LATENCY,P90_LATENCY,P99_LATENCY,STDDEV_LATENCY

when foo is passed to -o one will get those all on one line of CSV.
To -O one gets three lines of more netperf-classic-like "human"
readable output, and when one passes that to -k one gets a string of
keyval output a la:

raj@tardy:~/netperf2_trunk$ src/netperf -t omni -j -v 2 -- -r 1 -d rr -k foo
OMNI TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost
(127.0.0.1) port 0 AF_INET : histogram
THROUGHPUT=29454.12
THROUGHPUT_UNITS=Trans/s
RT_LATENCY=33.951
MIN_LATENCY=19
MEAN_LATENCY=32.00
MAX_LATENCY=126
P50_LATENCY=32
P90_LATENCY=38
P99_LATENCY=41
STDDEV_LATENCY=5.46

Histogram of request/response times
UNIT_USEC     :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
TEN_USEC      :    0: 3553: 45244: 237790: 7859:   86:   10:    3:    0:    0
HUNDRED_USEC  :    0:    2:    0:    0:    0:    0:    0:    0:    0:    0
UNIT_MSEC     :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
TEN_MSEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
HUNDRED_MSEC  :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
UNIT_SEC      :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0
TEN_SEC       :    0:    0:    0:    0:    0:    0:    0:    0:    0:    0

quoted

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