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Re: [PATCH -tip 0/9] perf-probe updates
- From: Ingo Molnar <mingo at elte dot hu>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: Frederic Weisbecker <fweisbec at gmail dot com>, lkml <linux-kernel at vger dot kernel dot org>, Steven Rostedt <rostedt at goodmis dot org>, Jim Keniston <jkenisto at us dot ibm dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, "Frank Ch. Eigler" <fche at redhat dot com>, Jason Baron <jbaron at redhat dot com>, "K.Prasad" <prasad at linux dot vnet dot ibm dot com>, Peter Zijlstra <peterz at infradead dot org>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Arnaldo Carvalho de Melo <acme at redhat dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Tue, 1 Dec 2009 08:29:02 +0100
- Subject: Re: [PATCH -tip 0/9] perf-probe updates
- References: <20091201001912.10235.79411.stgit@harusame>
* Masami Hiramatsu <mhiramat@redhat.com> wrote:
> Hi,
>
> Here are bugfixes and updates for perf-probe and kprobe-tracer. I've
> fixed some minor bugs and added --list option and simple probe naming.
Applied, thanks Masami!
> TODO:
> - Support build-id checking.
> - Support --del option to remove probes.
> - Support --line option to show which lines user can probe.
> - Support lazy string matching.
ok, cool!
One other small detail i noticed wrt. probe naming. Right now if we
insert a single probe into a function it gets named schedule_0:
# perf probe schedule
Could not open vmlinux/module file. Try to use symbols.
Added new event: p:probe/schedule_0 schedule+0
the next one gets named schedule_1, schedule_2, etc.
It would be nice to special-case the first one and name it 'schedule'.
Most of the time people insert a single probe into a function, so the _0
postfix is extra and in most cases unnecessary typing for them.
Another small detail is that i dont think we should emit this line:
Could not open vmlinux/module file. Try to use symbols.
when we can create a probe successfully - it's just unnecessary noise,
the user does not care how we pulled it off, as long as we were able to
get a reliable symbol address and the insertion worked fine.
A third detail is this line:
Added new event: p:probe/schedule_0 schedule+0
If that is pasted to perf stat directly it wont work because the syntax
is probe:schedule_0. So i'd suggest to print something like:
Added new event: probe/schedule_0 (on schedule+0)
Perhaps even print another line:
You can now use it on all perf tools, such as:
perf probe -e probe/schedule_0 -a sleep 1
perf record -e probe/schedule_0 -a sleep 1
... to show people how to make use of it.
Thanks,
Ingo