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. 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
>100_SECS: 0
HIST_TOTAL: 294547
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