Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751215AbaKEGXr (ORCPT <rfc822;w@1wt.eu>);
	Wed, 5 Nov 2014 01:23:47 -0500
Received: from lgeamrelo02.lge.com ([156.147.1.126]:50600 "EHLO
	lgeamrelo02.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750844AbaKEGXq (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 5 Nov 2014 01:23:46 -0500
X-Original-SENDERIP: 10.177.222.235
X-Original-MAILFROM: namhyung@gmail.com
From: Namhyung Kim <namhyung@kernel.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, srikar@linux.vnet.ibm.com,
        Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Brendan Gregg <brendan.gregg@gmail.com>, yrl.pp-manager.tt@hitachi.com,
        Hemant Kumar <hemant@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH perf/core 0/6] perf-probe: Bugfix and add new options for cache
References: <20141031185128.27889.32747.stgit@localhost.localdomain>
	<20141031121301.GI1313@kernel.org> <545770E6.2010506@hitachi.com>
	<20141103161900.GA18464@kernel.org> <545857CF.3060709@hitachi.com>
	<20141104143814.GH18464@kernel.org> <5458FD56.8040304@hitachi.com>
Date: Wed, 05 Nov 2014 15:23:44 +0900
In-Reply-To: <5458FD56.8040304@hitachi.com> (Masami Hiramatsu's message of
	"Wed, 05 Nov 2014 01:22:46 +0900")
Message-ID: <87h9yew4gf.fsf@sejong.aot.lge.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 05 Nov 2014 01:22:46 +0900, Masami Hiramatsu wrote:
> (2014/11/04 23:38), Arnaldo Carvalho de Melo wrote:
>> Em Tue, Nov 04, 2014 at 01:36:31PM +0900, Masami Hiramatsu escreveu:
>>> OK, I agree using .debug/.buildid/ to store caches.
>>> Here is what I'm thinking,
>>  
>>>   # this makes caches for given pattern instead of adding probes.
>>>   perf probe --cache '* $params'
>> 
>>>   # the cache is stored in .debug/.buildid/<buildid>.probe
>>>   # the cache entry can be queried by buildid and eventname
>> 
>> To follow the existing standard this would instead go to:
>> 
>>>   # the cache is stored in .debug/probes/path/to/dso/name/buildid
>>>   # And can be found via its buildid link .debug/.buildid/bu/ildid -> ../../probes/path/to/dso/name/buildid
>
> Ah, I see. so you meant adding a top-level .debug/probes/ dir.
> But in that case, shouldn't we change .debug/.buildid/bu/ildid to
> .debug/probes/.buildid/bu/ildid ?

Either is fine to me.  But my concern is that it might be bloated as
system/package update is going on, so we need to control it somehow.
That's why I suggested the probe-cache command.

>
>> 
>>>   perf probe --query ${remote_buildid}:do_fork
>>>   p:probe/do_fork _text+298722 clone_flags=%di:u64 stack_start=%si:u64 stack_size=%dx:u64 parent_tidptr=%cx:u64 child_tidptr=%r8:u64
>> 
>>>   # or perf can set it up directly to local
>>>   perf probe --query-add do_fork
>> 
>> You missed the build id above, no? I.e. it would be:
>> 
>>>   # or perf can set it up directly to local
>>>   perf probe --query-add ${remote_buildid}:do_fork
>
> No, since this command set the event to local machine, perf-probe
> should check the local build-id and query the appropriate event
> from the cache.
> # BTW, maybe we'd better use perf probe --add '$do_fork' (calls
> # "cache of do_fork")  instead of long --query-add. :)

It should take care of uprobe case too.  So simple do_fork should have
group/event or provider/marker form instead so that it can help to find
which binary defines the cached event.  Maybe we also need to keep a
event-to-binary table and then check (current?) build-id somehow to
identify correct event to be used.

Also this function entry level event cache can be used with uprobes..

Thanks,
Namhyung
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/