NPTL Trace Tool

GLIBC PATCH

The NPTL is part of the GNU C library (glibc). When building the glibc, several dynamic libraries are actually built. The NPTL corresponds to the file libpthread.so.

To trace the thread library, trace points needs to be inserted into the NPTL. PTT comes with a patch for the glibc, which includes:

• trace points inserted into NPTL routines.
• PTT module files that define functions used to collect trace point data.
• additionnal options in glibc configuration files (configure.in, configure, config.h.in, config.make.in).
• a modified nptl/Makefile.

All things added in NPTL code are enclosed in preprocessor directives, thus allowing to build the glibc in two different ways:

• if nothing special is done, the original glibc is built.
• using --with-ptt in the glibc ./configure script builds the glibc with PTT support. This means that the built libpthread.so will contain instructions to trace NPTL events. These instructions will be run only if the PTT daemon is previously launched.