From: Masami Hiramatsu <mhiramat@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
Ingo Molnar <mingo@elte.hu>,
LKML <linux-kernel@vger.kernel.org>,
systemtap-ml <systemtap@sources.redhat.com>,
Hideo AOKI <haoki@redhat.com>
Subject: Re: [RFC] Tracepoint proposal
Date: Tue, 24 Jun 2008 11:06:00 -0000 [thread overview]
Message-ID: <48606553.8070503@redhat.com> (raw)
In-Reply-To: <20080622171135.GA19432@Krystal>
Hi Mathieu,
Mathieu Desnoyers wrote:
>
> Hi Peter,
>
> I've tried to read through the comments recently posted to this thread
> (sorry I don't have time to answer them all specifically right now, a
> lot of this makes a lot of sense). I've tried to come up with a
> proposal, let's name it "tracepoint", which should hopefully address the
> full scope of the problem. Please tell me if it makes sense. It should
> allow compile-time verification of dynamically linked-in and activated
> tracepoints. I'll work on an implementation ASAP.
>
> Mathieu
>
> Tracepoint proposal
>
> - Tracepoint infrastructure
> - In-kernel users
> - Complete typing, verified by the compiler
> - Dynamically linked and activated
>
> - Marker infrastructure
> - Exported API to userland
> - Basic types only
>
> - Dynamic vs static
> - In-kernel probes are dynamically linked, dynamically activated, connected to
> tracepoints. Type verification is done at compile-time. Those in-kernel
> probes can be a probe extracting the information to put in a marker or a
> specific in-kernel tracer such as ftrace.
> - Information sinks (LTTng, SystemTAP) are dynamically connected to the
> markers inserted in the probes and are dynamically activated.
>
> - Near instrumentation site vs in a separate tracer module
>
> A probe module, only if provided with the kernel tree, could connect to internal
> tracing sites. This argues for keeping the tracepoing probes near the
> instrumentation site code. However, if a tracer is general purpose and exports
> typing information to userspace through some mechanism, it should only export
> the "basic type" information and could be therefore shipped outside of the
> kernel tree.
>
> In-kernel probes should be integrated to the kernel tree. They would be close to
> the instrumented kernel code and would translate between the in-kernel
> instrumentation and the "basic type" exports. Other in-kernel probes could
> provide a different output (statistics available through debugfs for instance).
> ftrace falls into this category.
>
> Generic or specialized information "sinks" (LTTng, systemtap) could be connected
> to the markers put in tracepoint probes to extract the information to userspace.
> They would extract both typing information and the per-tracepoint execution
> information to userspace.
Your idea is good to me. I just worry about complexity.
if both tracepoint and marker add information to other sections,
both two functions cover each partially. Anyway, it depends
on implementation.:-)
> Therefore, the code would look like :
>
> kernel/sched.c:
>
> #include "sched-trace.h"
>
> schedule()
> {
> ...
> trace_sched_switch(prev, next);
> ...
> }
>
>
> kernel/sched-trace.h:
>
> DEFINE_TRACE(sched_switch, struct task_struct *prev, struct task_struct *next);
>
>
> kernel/sched-trace.c:
>
> #include "sched-trace.h"
>
> static probe_sched_switch(struct task_struct *prev, struct task_struct
> *next)
> {
> trace_mark(kernel_sched_switch, "prev_pid %d next_pid %d prev_state %ld",
> prev->pid, next->pid, prev->state);
> }
>
> int __init init(void)
> {
> return register_sched_switch(probe_sched_switch);
> }
>
> void __exit exit(void)
> {
> unregister_sched_switch(probe_sched_switch);
> }
>
>
> Where DEFINE_TRACE internals declare a structure, a trace_* inline function,
> a register_trace_* and unregister_trace_* inline functions :
Hmm, if so, DEFINE_TRACE() still needs next and prev.:-)
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
prev parent reply other threads:[~2008-06-24 3:10 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-20 19:36 [RFC][Patch 2/2] markers: example of irq regular kernel markers Masami Hiramatsu
2008-06-20 22:16 ` Mathieu Desnoyers
2008-06-20 23:23 ` Masami Hiramatsu
2008-06-21 15:08 ` KOSAKI Motohiro
2008-06-21 18:04 ` Steven Rostedt
2008-06-21 19:41 ` Frank Ch. Eigler
2008-06-22 4:03 ` Steven Rostedt
2008-06-22 4:32 ` Peter Zijlstra
2008-06-22 17:12 ` Frank Ch. Eigler
2008-06-23 2:20 ` Masami Hiramatsu
2008-06-23 7:08 ` KOSAKI Motohiro
2008-06-22 18:03 ` Frank Ch. Eigler
2008-06-22 18:27 ` Masami Hiramatsu
2008-06-21 10:14 ` Peter Zijlstra
2008-06-23 3:06 ` [RFC] Tracepoint proposal Mathieu Desnoyers
2008-06-23 6:34 ` Alexey Dobriyan
2008-06-23 6:51 ` Mathieu Desnoyers
2008-06-24 7:15 ` Alexey Dobriyan
2008-06-24 11:39 ` Masami Hiramatsu
2008-06-24 13:23 ` Takashi Nishiie
2008-06-24 16:23 ` Frank Ch. Eigler
2008-06-24 19:43 ` Masami Hiramatsu
2008-06-25 1:08 ` KOSAKI Motohiro
2008-06-25 1:36 ` Masami Hiramatsu
2008-06-25 1:49 ` Mathieu Desnoyers
2008-06-26 16:20 ` [RFC PATCH] Tracepoint sched probes Mathieu Desnoyers
2008-06-26 17:01 ` [RFC PATCH] Kernel Tracepoints Mathieu Desnoyers
2008-06-27 13:21 ` Masami Hiramatsu
2008-06-27 15:00 ` Mathieu Desnoyers
2008-06-29 18:46 ` Masami Hiramatsu
2008-06-30 18:21 ` Mathieu Desnoyers
2008-06-27 15:07 ` Mathieu Desnoyers
2008-06-30 20:11 ` Masami Hiramatsu
2008-06-27 15:48 ` Mathieu Desnoyers
2008-06-28 0:05 ` Masami Hiramatsu
2008-06-30 17:14 ` Mathieu Desnoyers
2008-06-30 20:17 ` Masami Hiramatsu
2008-07-03 15:13 ` Mathieu Desnoyers
2008-07-03 18:53 ` Masami Hiramatsu
2008-06-27 16:11 ` [RFC PATCH] Kernel Tracepoints (update) Mathieu Desnoyers
2008-07-03 15:29 ` Masami Hiramatsu
2008-07-03 15:47 ` Mathieu Desnoyers
2008-07-03 18:19 ` Mathieu Desnoyers
2008-07-03 18:48 ` Masami Hiramatsu
2008-06-24 11:06 ` Masami Hiramatsu [this message]
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