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Re: [opensuse] Including a NPTL Trace Tool in Suse
  • From: Guillaume Duranceau <guillaume.duranceau@xxxxxxxx>
  • Date: Fri, 28 Apr 2006 09:35:25 +0200
  • Message-id: <200604280935.25241.guillaume.duranceau@xxxxxxxx>
Hello,

Michael K Dolan Jr wrote:
> How is this the same/similar to SystemTap?
>
> > I'm currently working on an opensource project that aims to trace NPTL
> > routines in order to help users to analyze and understand performance
> > problems and/or debug their multi-threaded applications. This tool, named
> > PTT (Posix Thread Trace Toolkit), shows NPTL routines calls and exits, as
> > well as internal mechanisms details of the library, with a very low
> > impact on performance. PTT can save a lot of time when debugging complex
> > (or even simpler) multi-threaded programs that don't behave as expected.

According to what I read in SystemTap documentation, it is used to get
information about events happening in the kernel (tell me if I'm wrong). PTT
shows you NOTHING about the kernel. It's a user space tool which adds trace
points into the glibc thread library (NPTL). These trace points never make
system calls to not disturb multi-threaded applications dynamic.

There are 2 types of NPTL events that PTT handles:
- calls to and exits from NPTL routines.
- internal NPTL events, caused by modification of properties of NPTL objects
(for example, when locks are taken or freed, when mutex values change...)

The collection of events recorded during a program execution helps you to
understand what really happens inside your multi-threaded application.

See http://nptltracetool.sourceforge.net/ for more details.

Regards,
Guillaume

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