lkml.org 
[lkml]   [2008]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC] LTTng merge plan
    * Frank Ch. Eigler (fche@redhat.com) wrote:
    > Hi, Mathieu -
    >
    > > [...]
    > > Currently, [my merge plan] looks like :
    > >
    > > In Ingo's trees :
    > > - Tracepoints, scheduler tracepoints instrumentation, ftrace port to
    > > tracepoints
    > > - Should make it into 2.6.27 since ftrace needs those.
    > > [...]
    >
    > This is the tracepoints infrastructure, and ...
    >
    > > Short-term submission plan
    > >
    > > In LTTng patchset
    > > (http://ltt.polymtl.ca/lttng/patch-2.6.26-0.12.tar.bz2)
    > >
    > > - Instrumentation
    > > - LTTng tracepoints
    > > - Used by LTTng, SystemTAP and usable specialized probes.
    > > [...]
    >
    > ... this is the "meat", which includes both the tracepoints
    > and the the tracepoint-to-marker conversion modules, such as those in
    > "lttng-instrumentation-*-tracepoint-probes.patch", right?
    >
    > - FChE

    Exactly. The tracepoint-to-markers conversion modules bridge between
    the in-kernel API (tracepoints) which declares standard location for
    kernel instrumentation and user-space visible "markers", so that there
    is an indirection level between the instrumented kernel code and what is
    visible from userspace.

    For instance, we have

    in kernel/sched.c:context_switch()
    trace_sched_switch(rq, prev, next);

    Which exports a struct rq * and two struct task_struct *. They are used
    by both ftrace, which needs access to these data structures, and by the
    LTTng probes, which extracts the previous PID and state (running,
    waiting..) and next PID to be scheduled in.

    Basically, these modules turn the data exported by tracepoints,
    meaningful only to kernel modules, into data useful for userspace trace
    analysis.

    Mathieu

    --
    Mathieu Desnoyers
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68


    \
     
     \ /
      Last update: 2008-07-29 19:05    [W:0.025 / U:0.080 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site