Analysing traces for performance bottlenecks
sam_mailinglists at spacething.org
Thu Jul 17 10:52:51 CDT 2008
Matt Cable wrote:
> Kevin Oberman <oberman <at> es.net> writes
>> tcptrace is old and pretty basic, but it can provide a LOT if
>> information. Combined with xplot, the graphs often point to the exact
>> nature of a TCP problem, but you need a really good understanding of TCP
>> to figure anything out.
> Wireshark also provides tcptrace-like graphs ("Statistics -> TCP Stream Graph ->
> Time Sequence Graph (tcptrace)"). They're not quite as pretty, but are just as
> effective at tracking down all sorts of TCP problems, provided, as Kevin said,
> you have a really good understanding of how TCP behaves
Thanks for all the replies so far. While the TCP graphs are useful they
are very difficult to read in Wireshark - they really need to be
displayed in xplot, but this requires an X11 setup?
I've found NDT:
This uses a java applet hosted on a web100 patched linux server to
record network diagnostics from connecting clients. A typical report
might look like this:
Web100 reports the Round trip time = 122.15 msec; the Packet size =
1260 Bytes; and
No packet loss was observed.
C2S throughput test: Packet queuing detected: 1.09%
S2C throughput test: Packet queuing detected: 1.32%
This connection is receiver limited 84.33% of the time.
Increasing the the client's receive buffer (63.0 KB) will improve
This connection is sender limited 1.70% of the time.
Increasing the NDT server's send buffer (127.0 KB) will improve
This connection is network limited 13.96% of the time.
The theoretical network limit is 7869.69 Mbps
The NDT server has a 127.0 KByte buffer which limits the throughput
to 16.37 Mbps
Your PC/Workstation has a 63.0 KByte buffer which limits the
throughput to 4.09 Mbps
The network based flow control limits the throughput to 8.73 Mbps
Client Data reports link is 'OC-48', Client Acks report link is 'OC-12'
Server Data reports link is 'OC-48', Server Acks report link is 'T3'
Something that could provide a similar, automated analysis of a TCP
stream capture is what I'm after, although I doubt a standard packet
capture will be able to provided as many metric as web100 stack can.
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