linux-kernel - Re: [PATCH -tip perf/probes 00/10] x86 insn decoder bugfixes and perf-probe syntax changes

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Message-ID: <4AEF4C29.2060501@redhat.com>
Date:	Mon, 02 Nov 2009 16:16:25 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frédéric Weisbecker 
	<fweisbec@...il.com>, lkml <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Jim Keniston <jkenisto@...ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Jason Baron <jbaron@...hat.com>,
	"K.Prasad" <prasad@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>
Subject: Re: [PATCH -tip perf/probes 00/10] x86 insn decoder bugfixes and
 perf-probe syntax changes

Masami Hiramatsu wrote:
> Ingo Molnar wrote:
>> What we want here is two fold:
>>
>>    - enable kprobes event support when perf events is enabled and kprobes
>>      is enabled. We dont want another config option for it.
>
> Sure, at least that combination should enable kprobe-tracer forcibly.

Hmm, someone may not want to enables kprobe-tracer. Perhaps,
"default y if (EVENT_PROFILE)" is enough, isn't it?


>> A few further (and very small) UI tweaks i'd suggest:
>>
>> Firstly, could we please make the first probe inserted named plain after
>> the symbol it specifies, with no _0 postfix? I.e. instead of:
>>
>>              7358  perfprobe:__switch_to_0  #      0.000 M/sec
>>
>> we'd get:
>>
>>              7358  perfprobe:__switch_to    #      0.000 M/sec
>>
>> Subsequent probes for the same symbol can be named _1, _2 - but the
>> first symbol should not have this needless post-fix.
>
> Ah, this prefix means the offset from the symbol. Of course we can
> remove it if the offset == 0. Or, would you think make the postfix
> sequence number of probes on the same symbol?

If so, we'd better have --list option before that and check the
postfix is already used, since we may not want to overwrite
existing probes, right?

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

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