A library that tracks the queuing time of bytes traveling through the kernel
- cmake
- glib
- zlib
- pcap
sudo yum install cmake glib2 glib2-devel zlib zlib-devel libpcap libpcap-devel
sudo apt-get install cmake libglib2.0 libglib2.0-dev zlib1g zlib1g-dev libpcap-dev
An out of source build, and local install is recommended:
cd libkqtime
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/home/${USER}/.local
make
make install
Build options are specified as -D<option>:
CMAKE_BUILD_TYPE=Debug- enable verbose debug messagesCMAKE_INSTALL_PREFIX=path/to/install- installation root path
Using libkqtime in your application is relatively straightforward. There are four main steps:
- Initialize Library Resources
- Regsiter Sockets
- Deregister Sockets
- Free Library Resources
The library is initialized with kqtime_new. Then, the application manages the sockets that the library should measure by calling kqtime_register and kqtime_deregister. When finished, the library resources are freed with kqtime_free.
The kqtime_new function takes a filepath as an argument. It logs the kernel statistics to a file of that name. If the filepath ends in .gz, then the file will be compressed inline with zlib. For example, calling
kqtime_new("kqtime.log.gz", 1, 1, 1)
would produce a file kqtime.log.gz in the current directory containing the logged statistics.
A socket name (an arbitrary string) may be passed into libqtime when registering a socket with kqtime_register. libkqtime will append this string to every log message pertaining to the registered socket.
Use the scripts in the tools directory to transform the data collected in the log file by libkqtime into graphs:
zcat kqtime.log.gz | xz -T 6 > kqtime.log.xz
xzcat kqtime.log.xz | pypy tools/parse-kqtime.py | xz -T 6 > kqtime.dat.xz
xzcat kqtime.dat.xz | python tools/plot-kqtime.py
Then check for the .pdf files in the current directory.
See this branch for the modifications made to Tor to make use of libkqtime.
git clone https://github.com/robgjansen/tor.git
cd tor
git checkout -b kqtime origin/support/kqtime
This gives a new config option that can be used like: KQTimeLogFile "/home/${USER}/tor/kqtime.log.gz". This filepath will be passed into the kqtime_new function, and statistics will be collected for all sockets created by Tor.
Assuming libkqtime was installed to /home/${USER}/.local, and using the torclone branch from above, Tor should be compiled as follows:
LD_LIBRARY_PATH=/home/${USER}/.local/lib/ CFLAGS="-I/home/${USER}/.local/include" LDFLAGS="-L/home/${USER}/.local/lib" LIBS="-lkqtime" ./configure --disable-asciidoc
Root privileges are required because libkqtime uses libpcap to capture packets in real time.
sudo LD_LIBRARY_PATH=/home/${USER}/.local/lib/ LD_PRELOAD=/home/${USER}/.local/lib/libkqtime-preload.so ./src/or/tor