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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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