Hi Sazzad,
what is the value of the from field i the structure sctp_cwnd_log?
Best reards
Michael
On Jan 23, 2009, at 1:16 AM, Rahman, Md Sazzadur wrote:
Hi Randall,
Thanks for your suggestions. I could collect congestion window data
from SCTP sender using SCTP_LOCAL_TRACE_BUF on FreeBSD7.1 kernel
using the tools you provided (dump_apple_log.c, prtcwndlog.c etc.).
Now, in the log, I found that tsn (Transmission Sequence Number)
never changes and remains fixed which is not supposed to happen, I
believe. Do you have any idea what could go wrong?
For example, in the log below, tsn is always 28170ae0.
//-From Log-------------------------------
2.162922 1543161849724545 Network:0xc463aaf0 cwnd:13063 flight:
12762 pq:f4f72484 Log from a Send tsn:28170ae0 (sendcnt:191,strcnt:
191)
2.200947 1543161849753090 Network:0xc463aaf0 cwnd:13063 flight:
14180 pq:f4f72484 Log from a Send tsn:28170ae0 (sendcnt:191,strcnt:
191)
..............
.............
2592.987776 1543168861292865 Network:0xc463aaf0 cwnd:13063 flight:
14180 pq:f4f72484 Log from a Send tsn:28170ae0 (sendcnt:191,strcnt:
191)
//----------------------------------------------
Steps I have followed:
//----------------------------------------------
1. Recompiled FreeBSD7.1 kernel by enabling SCTP_LOCAL_TRACE_BUF
#define SCTP_LOCAL_TRACE_BUF 1
2. Enalble desired loging using sysctl;
Sysctl -w "net.inet.sctp.log_level=0x00000004
3. Run application that sends SCTP data to the network
4. ./Dump_apple_log > data.txt
5. ./Prtcwdlog -l data.txt> cwnd.txt
//----------------------------------------------
I have attached the log file herewith this mail.
It would be great if you can give me any hint to resolve this issue.
Thanks,
Sazzad
-----Original Message-----
From: Randy Stewart [mailto:rand...@lakerest.net]
Sent: Thursday, August 28, 2008 6:39 AM
To: sazzadur rahman
Cc: freebsd-net; Atiquzzaman, Mohammed; Rahman, Md Sazzadur
Subject: Re: A query regarding SCTP congestion control
Remember a lot has changed between the book and now.
1) The initial window is now different
2) labc variable may influence how the cwnd responds
are just 2 off the top of my head.
You also may want to use a local trace buffer (as I mentioned earlier)
since
turning KTR on really really skew's things time wise.. its a resource
pig.
We added the local trace buffer for this very reason.
Contact me directly if you need guidance on this. Also you may want
to pick up the latest update that I just put up on www.sctp.org
It gets the 7.0 stack current to 8.0's code.. .and there have
been at least 1 CC fix in the last few months..
R
On Jul 2, 2008, at 2:37 PM, sazzadur rahman wrote:
Hello,
I need to get SCTP congestion window data for research purpose. I
collected
cwnd data from SCTP sender running on FreeBSD 7.0 machine by using
KTR
kernel log. After that, I tried to plot cwnd vs. time and generated
graph.
But I am unable to explain the graph and it is very different
compared to
the graph as shown in the book "Stream Control Transmission Protocol
(SCTP)", a reference guide by Randall R. Stewart, page 187 and TCP
congestion window. An typical entry from the log looks like:
749199232185105 Net:0xc7703000 at cwnd_event (SACK) cwnd:25140
flight:0 pq:0
atpc:72 needpc:235 (tsn:0,sendcnt:191,strcnt:191)
I have used 749199232185105 in x axis as time and cwnd:25140 in y
axis. I
have attached the image file of the graph herewith this mail.
From the log, I found that cwnd varies very frequently accross
time. Does
anyone have any idea regarding this issue?
Please let me know if you have any questions further.
Thanks in advance.
Best regards,
Md Sazzadur Rahman
Graduate Student,
School of Computer Science,
University of Oklahoma,
Norman, Oklahoma, USA
Steps for getting kernel log
------------------------------------------
1. Add options:
options KTR
options KTR_ENTRIES=65536
options KTR_MASK=KTR_SUBSYS
2. Recompile kernel
config CUSTOM_KERNEL_9_6
cd ../compile/ CUSTOM_KERNEL_9_6
make cleandepend;make depend;
make all install
3. Tried to enable trace point by:
Sysctl -w "net.inet.sctp.log_level=0x00000004"
4. run SCTP sender.
5. pull out data:
Ktrdump -q -t -o file_name
Prtcwndlog -l filename > cwnd.txt
---------------------------------------------------
On Wed, Apr 16, 2008 at 9:03 AM, Randall Stewart <r...@cisco.com>
wrote:
Rahman, Md Sazzadur wrote:
Hi, I would like to get the values of SCTP congestion control
algorithm variables (cwnd, ssthresh, flightsize and pba) from any
SCTP based application in runtime for research purpose. Does any
API
exist in SCTP for that? Do I need to dig the SCTP code in kernel
to
get the values?
There is a socket option to get the cwnd.
However, I think what you really want is some of the researchish
tracing stuff that SCTP provides.
You can actually get a real time trace of the cwnd/flight etc via
the
various logging functions.
You basically must compile this as an option.. have to go look
at the options..
And then you can either use ktrace (which I don't recommend since
it turns on to much overhead in the kernel) or you can
use SCTP_LOCAL_TRACE_BUF
This will put it into a piece of memory only for SCTP and
not turn on all the other ktrace points.
After you enable the logging in your compile you must turn
on the logging level..
SCTP_CWND_LOGGING_ENABLE
woudl be my recommendation.
It gives you a real time up/down growth of the cwnd/flight/rwnd
I think I wrote a "how to" somewhere.. let me go look..
R
I will appreciate any help in this regard.
Best Regards, Md Sazzadur Rahman Graduate Student, School of
Computer
Science, University of Oklahoma, Norman, Oklahoma, USA
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