From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
ltt-dev@lists.casi.polymtl.ca,
Linus Torvalds <torvalds@linux-foundation.org>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [ltt-dev] [PATCH] Simple LTTng userspace events through debugfs
Date: Tue, 16 Dec 2008 23:16:28 -0500 [thread overview]
Message-ID: <20081217041628.GA5409@Krystal> (raw)
In-Reply-To: <20081216194201.GE843@elte.hu>
* Ingo Molnar (mingo@elte.hu) wrote:
>
> * Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:
>
> > Hi,
> >
> > I looked at kmemtrace and noticed that the presence of a debugfs
> > "marker" file, which lets userspace write events into the trace buffers.
> >
> > So I just did the same with a
> >
> > /debugfs/ltt/write_event
>
> you mean similar to ftrace's /debug/tracing/trace_marker ? ;-)
>
Quite similar, yes :)
Looking at tracing_mark_write(), I am wondering if the fact that it
returns a count including the added \n is an expected side effect ? A
write() returning a count larger than the number of bytes written seems
to be a bit unexpected... But if we remove the \n from the count, then
the case where one write \0 into the event content would end up doing an
endless loop.
Mathieu
> Ingo
>
> _______________________________________________
> ltt-dev mailing list
> ltt-dev@lists.casi.polymtl.ca
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
next prev parent reply other threads:[~2008-12-17 4:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-15 23:10 [PATCH] Simple LTTng userspace events through debugfs Mathieu Desnoyers
2008-12-16 19:42 ` Ingo Molnar
2008-12-17 4:16 ` Mathieu Desnoyers [this message]
2008-12-17 17:32 ` [ltt-dev] " Mathieu Desnoyers
2008-12-18 16:50 ` Randy Dunlap
2008-12-18 16:58 ` Mathieu Desnoyers
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