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    SubjectRe: [PATCH 0/4][RFC] event tracer
    * Steven Rostedt (rostedt@goodmis.org) wrote:
    >
    > This is still RFC, do not pull.
    >
    > This patch set gives the ability to add a format string and args to
    > a trace point declaration. Then it gives a tracer an opportunity to
    > override the header macro and use the default trace format to trace
    > the object.
    >
    > For example (and used in this patch series), the sched tracepoint
    > declarations are moved from include/trace/sched.h to
    > include/trace/sched_event_types.h, and instead of using the macro
    > DECLARE_TRACE we use DECLARE_TRACE_FMT. The first three arguments
    > are the same, but it adds 2 more arguments. A printf format and
    > arguments.
    >
    > The new trace/sched.h file contains:
    >
    > #include <linux/sched.h>
    > #include <linux/tracepoint.h>
    >
    > #include <trace/sched_event_types.h>
    >
    > The sched_event_types.h file has:
    >
    > DECLARE_TRACE_FMT(sched_kthread_stop,
    > TPPROTO(struct task_struct *t),
    > TPARGS(t),
    > "task %s:%d", TPARGS(t->comm, t->pid));
    >
    > The tracepoint.h defines DECLARE_TRACE_FMT as:
    >
    > #define DECLARE_TRACE_FMT(name, proto, args, fmt, fmt_args) \
    > DECLARE_TRACE(name, TPPROTO(proto), TPARGS(args))
    >
    >
    > But in kernel/trace/events.c we have:
    >
    > /* trace/<type>.h here */
    > #include <trace/sched.h>
    >
    > #include "trace_events.h"
    >
    > /* trace/<type>_event_types.h here */
    > #include <trace/sched_event_types.h>
    >
    > The trace_events.h redefines the DECLARE_TRACE_FMT and makes a hook
    > for to automate adding event points.
    >
    > To add event points, convert to the DECLARE_TRACE_FMT, add your default
    > printf format, and then add to events.c, the <type>.h and <type>_event_types.h
    > as described. Then your trace points will appear in the event tracer.
    >
    > Next I'll convert the rest of the tracepoints that are already defined
    > to this format.
    >

    Hi Steve,

    The approach sounds great : an hybrid between markers and tracepoints.
    I'll dig into it. That would be useful for LTTng.

    Mathieu

    >
    > The following patches are in:
    >
    > git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
    >
    > branch: rfc/event_tracer
    >
    >
    > Steven Rostedt (4):
    > tracing: add event trace infrastructure
    > tracing: add DECLARE_TRACE_FMT to tracepoint.h
    > tracing: add schedule events to event trace
    > tracing: make event directory structure
    >
    > ----
    > include/asm-generic/vmlinux.lds.h | 11 +-
    > include/linux/tracepoint.h | 3 +
    > include/trace/sched.h | 49 +-----
    > include/trace/sched_event_types.h | 74 +++++++
    > kernel/trace/Kconfig | 9 +
    > kernel/trace/Makefile | 2 +
    > kernel/trace/events.c | 13 ++
    > kernel/trace/trace_events.c | 407 +++++++++++++++++++++++++++++++++++++
    > kernel/trace/trace_events.h | 52 +++++
    > 9 files changed, 571 insertions(+), 49 deletions(-)
    > --
    >

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


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