Re: Re: [RFC PATCH perf/core v2 16/16] perf probe: Accept %sdt and %cached event name

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-kernel@vger.kernel.org,
	Adrian Hunter <adrian.hunter@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Paul Mackerras <paulus@samba.org>,
	Jiri Olsa <jolsa@kernel.org>, Borislav Petkov <bp@suse.de>,
	Hemant Kumar <hemant@linux.vnet.ibm.com>
Subject: Re: Re: [RFC PATCH perf/core v2 16/16] perf probe: Accept %sdt and %cached event name
Date: Mon, 20 Jul 2015 12:03:34 +0900	[thread overview]
Message-ID: <55AC6506.5040003@hitachi.com> (raw)
In-Reply-To: <20150719105359.GC25163@danjae.kornet>

On 2015/07/19 19:53, Namhyung Kim wrote:
> On Wed, Jul 15, 2015 at 06:15:44PM +0900, Masami Hiramatsu wrote:
>> To improbe usability, support %[PROVIDER:]SDTEVENT format to
>> add new probes on SDT and cached events.
> 
> Ah, you meant we can skip the provider if the event name is unique..

Right, that's easier for users.

>>
>> e.g.
>>   ----
>>   # perf probe -x /lib/libc-2.17.so  %lll_lock_wait_private
> 
> Maybe we can also skip the target path (-x) too in this case.

Agreed. For that feature, we need to improve buildid-cache to get
all valid buildid caches (this means that it has to verify all the
cached binaries' buildid). Anyway, the same feature is required for
showing available cached probe-events on perf-list.

Thank you,

> 
> Thanks,
> Namhyung
> 
> 
>>   Added new event:
>>     libc:lll_lock_wait_private (on %lll_lock_wait_private in
>>   /usr/lib/libc-2.17.so)
>>
>>   You can now use it in all perf tools, such as:
>>
>>           perf record -e libc:lll_lock_wait_private -aR sleep 1
>>
>>   # perf probe -l | more
>>     libc:lll_lock_wait_private (on __lll_lock_wait_private+21
>>    in /usr/lib/libc-2.17.so)
>>   ----
>>
>> Note that this is not only for SDT events, but also normal
>> events with event-name.
>>
>> e.g. define "myevent" on cache (-n doesn't add the real probe)
>>   ----
>>   # perf probe -x ./perf --cache -n --add 'myevent=dso__load $params'
>>   ----
>>   Reuse the "myevent" from cache as below.
>>   ----
>>   # perf probe -x ./perf %myevent
>>   ----
>>
>> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
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-- 
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@hitachi.com