ndt-users list created

[Richard Carlson <>]

Hi Craig;

No, this NDT bug effects all servers.  I ran into it while testing from 
multiple clients.  Clients 2, 3, & 4 would get the "Other client testing 
please wait..." type message.  Client 2 would not get the final results 
until client 4 finished.  I'll add this patch to my next distribution, or 
you can apply it now if you are experiencing some problems.

Since this didn't fix Clay's problem, I may need to rethink how the tests 
are done.  Right now the server simply streams data out for 10 seconds, 
sending as much as it can.  Given the way TCP works, there is a probability 
that the server will build up a queue in the Send buffer (the bus is faster 
than the wire).  This buffer will need to drain before the test is 
complete.  Packet loss, or other factors could mean that this draining 
takes a long time so the client simply sits there waiting.  If it takes too 
long, the server process will time-out and terminate so the client will 
never get the final results.

More later.

Rich

At 08:26 AM 10/14/2005, Pepmiller, Craig E. wrote:
> Ok, so this is only seen when the NDT machine is configured for multiple
> simultaneous clients?
>
> Thanks-
> -Craig
>
> -----Original Message-----
> From: Richard Carlson 
> [mailto:]
> Sent: Wednesday, October 12, 2005 2:56 PM
> To: Clayton Keller; 
>
> Subject: Re: Slow Inbound Tests
>
> Hi Clayton;
>
> This is a bug in the web100srv code.  I forgot to shutdown the control
> socket at the end of the test.  If there are multiple clients then the
> final results are sent in a LIFO manner, so the first client needs to
> wait
> until all subsequent clients are done before the results are returned.
>
> I'll issue a patched version soon.  In the mean time you can patch your
> version by hand by adding the line "shutdown(ctlsockfd, SHUT_RDWR);" to
> the
> web100srv.c file (on line 1126).
>
> Let me know if that fixes things.
>
> Rich
>
>
> ---------------------------------------------------------------
> Original code:
>          if (admin_view == 1) {
>              totalcnt = calculate(SumRTT, CountRTT, CongestionSignals,
> PktsOut, DupAcksIn, AckPktsIn,
>                          CurrentMSS, SndLimTimeRwin, SndLimTimeCwnd,
> SndLimTimeSender,
>                          MaxRwinRcvd, CurrentCwnd, Sndbuf, DataBytesOut,
>
> mismatch, bad_cable,
>                          (int)bwout, (int)bwin, c2sdata, s2cack, 1,
> debug);
>              gen_html((int)bwout, (int)bwin, MinRTT, PktsRetrans,
> Timeouts,
>                          Sndbuf, MaxRwinRcvd, CurrentCwnd, mismatch,
> bad_cable, totalcnt,
>                          debug);
>          }
>
>          /* printf("Saved data to log file\n"); */
>
>          /* exit(0); */
> }
>
> main(argc, argv)
>
> ----------------------------------------------------------
> Modified code
>          if (admin_view == 1) {
>              totalcnt = calculate(SumRTT, CountRTT, CongestionSignals,
> PktsOut, DupAcksIn, AckPktsIn,
>                          CurrentMSS, SndLimTimeRwin, SndLimTimeCwnd,
> SndLimTimeSender,
>                          MaxRwinRcvd, CurrentCwnd, Sndbuf, DataBytesOut,
>
> mismatch, bad_cable,
>                          (int)bwout, (int)bwin, c2sdata, s2cack, 1,
> debug);
>              gen_html((int)bwout, (int)bwin, MinRTT, PktsRetrans,
> Timeouts,
>                          Sndbuf, MaxRwinRcvd, CurrentCwnd, mismatch,
> bad_cable, totalcnt,
>                          debug);
>          }
>          shutdown(ctlsockfd, SHUT_RDWR);
>          /* printf("Saved data to log file\n"); */
>
>          /* exit(0); */
> }
>
> main(argc, argv)
>
>
>
>
> At 01:54 PM 10/12/2005, Clayton Keller wrote:
> >I wanted to address this to the list. I believe there was a similar
> post a
> >week or so back but I wanted to address this clean.
> >
> >I currently have web100srv running from /etc/init.d/ndt with the
> following:
> >
> >/usr/local/sbin/web100srv -a -m -l /var/log/web100/web100srv.log
> >
> >The system is running on Fedora Core 4 using a patached 2.6.13 kernel
> from
> >kernel.org.
> >
> >The server itself is also sitting behind a PIX firewall.
> >
> >We have noticed that the Outbound Test will run rather quickly, but
> when
> >the Inbound, server to client, test is ran it can take upwards of
> several
> >minutes to complete, many times as much as 4 minutes. There are other
> >times where from the end user's point-of-view it appears the test never
>
> >completes although you can see results for the test appear in the
> >web100.log file. The test though will continue to sit on the unning 10s
>
> >inbound test (server to client) . . . . . .  portion of the test, and
> many
> >users are beginning to just close out the window.
> >
> >At this point I am looking for general issues that I can look into and
> >possibly run debug against as far as these tests are concerned.
> >
> >Clayton Keller
>
> ------------------------------------
>
>
>
> Richard A. Carlson                              e-mail:
>
> Network Engineer                                phone:  (734) 352-7043
> Internet2                                       fax:    (734) 913-4255
> 1000 Oakbrook Dr; Suite 300
> Ann Arbor,  MI  48104

------------------------------------



Richard A. Carlson                              e-mail: 

Network Engineer                                phone:  (734) 352-7043
Internet2                                       fax:    (734) 913-4255
1000 Oakbrook Dr; Suite 300
Ann Arbor,  MI  48104