Today I want to demonstrate how captcp outperform wireshark for TCP flow analysis. This posting focus on throughput analysis for a specific TCP flow. In a separate posting I will demonstrate how Gnuplot can be tweaked to generate a nice image ready for web publishing or for your bachelor/master/phd thesis. The need for this posting arise from discussions with captcp users where I think that the workflow with captcp and Gnuplot is not ideal....
back in the days, with black monitors, leather jackets, red phones, 5 1⁄4" floppy disks, … - I like via Amazon
Just for the statistical guys reading my blog: Jiri Olsa posted a patch today to extend perf diff to show differential profiling. Perf diff now support three diff computations: delta: the current default one ratio: ratio differential profile wdiff: weighted differential profile The idea goes back to Paul E. McKenney and his paper Differential Profiling. Nice reading!
For a new MANET protocol I started to verify the security concept. Not from a security point of view, rather from a protocol feasibility point of view. The security concept is based on existing security protocols. I just removed dynamic components like key exchange and the like (to be correct: dynamic aspects are done by special messages and not that tight linked with the protocol). The result should be a very lean TLV, containing only required security data without padding issues are “reserved” bits....
John Nagle (no, not the TCP Nagle ;-) proposed a extension to C to keep array information over the call context to do bounds checks. His proposal Safe Arrays and Pointers for C through compatible additions to the language is a nice reading. On the GCC maillinglist the responses are mixed: more questions and doubts if such a extension will and can be adopted by the users.
In the 32nd week I am on vacation in Switzerland in the mountains of Vallis. The picture is taken in Lötschental and the lake is called Schwarzsee. Only a few meters from our accommodation. The photo is taken by daoro
x86 Floating Point was and still is a source of problems. First of all the FPU (floating point coprocessor, x87) has 8 registers. Via gdb and info all-register you can display the floating point register. These registers are all 80 bit wide. And here the problems start: standardized are floating point math with 32 or 64 bit (float or double). If you compile the next construct with -m32 on a 32bit and a 64bit arch the results will differ:...
net-ping host --no=dns,bind --proto=TCP,rfc:492 eth0@ipv4::http://1.0.0.127.IN -ADDR.ARPA --stats -v ;-) from https://twitter.com/gitHater
Michael published the agenda for TCPM Vancouver Meeting and there are lot of items on the list this time. The following list is sorted by personal interest: Proportional Rate Reduction for TCP TCP Fast Open Increasing TCP’s Initial Window Impact of IW10 on Interactive Real-Time Communication Additional negotiation in the TCP Timestamp Option field during the TCP handshake TCP and SCTP RTO Restart More Accurate ECN Feedback in TCP TCP Loss Probe (TLP): An Algorithm for Fast Recovery of Tail Losses Evaluating TCP Laminar Highly Efficient Selective Acknowledgement (SACK) for TCP Shared Use of Experimental TCP Options A TCP Authentication Option NAT Extension RFC 1323bis HOST_ID TCP Options: Implementation and Preliminary Test Results Shared Memory Communications over RDMA Processing of IP Security/Compartment and Precedence Information by TCP Processing of TCP segments with Mirrored End-points I am especially interested in Ilpo’s Interactive Real-Time Communication IW10 talk....
Just a few bugfixes goes in since -rc7 so here we go: Linux 3.5 released. Changeset of upcoming 3.6 should be smaller because of vacation period.