linux-kernel - Re: [PATCH perf/core 00/22] perf refcnt debugger API and fixes

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Date:	Fri, 11 Dec 2015 10:53:38 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>,
	"'Arnaldo Carvalho de Melo'" <acme@...nel.org>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	"Namhyung Kim" <namhyung@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Alexei Starovoitov <ast@...mgrid.com>
Subject: Re: [PATCH perf/core  00/22] perf refcnt debugger API and fixes



On 2015/12/11 10:42, Wangnan (F) wrote:
>
>
> On 2015/12/11 10:15, 平松雅巳 / HIRAMATU，MASAMI wrote:
>> From: 'Arnaldo Carvalho de Melo' [mailto:acme@...nel.org]
>>> But this requires having these special refcnt__ routines, that will 
>>> make
>>> tools/perf/ code patterns for reference counts look different that the
>>> refcount patterns in the kernel :-\
>> BTW, I think even without the refcnt debugger, we'd better introduce 
>> this
>> kind API to unify the refcnt operation in perf code. As I said, we 
>> have many
>> miscodings on current implementation. Unifying the API can enforce 
>> developers
>> to avoid such miscodings.
>>
>> Thank you,
>>
>
> I tried this problem in another way, I'd like to share it here.
>
> First: create two uprobes:
>
> # ./perf probe --exec /home/wangnan/perf dso__new%return %ax
> Added new event:
>   probe_perf:dso__new  (on dso__new%return in /home/wangnan/perf with 
> %ax)
>
> You can now use it in all perf tools, such as:
>
>     perf record -e probe_perf:dso__new -aR sleep 1
>
> # ./perf probe --exec /home/wangnan/perf dso__delete dso
> Added new event:
>   probe_perf:dso__delete (on dso__delete in /home/wangnan/perf with dso)
>
> You can now use it in all perf tools, such as:
>
>     perf record -e probe_perf:dso__delete -aR sleep 1
>
>
> Then start test:
>
> # ./perf record -g -e probe_perf:dso__new -e probe_perf:dso__delete 
> ./perf probe vfs_read
> Added new event:
>   probe:vfs_read       (on vfs_read)
>
> You can now use it in all perf tools, such as:
>
>     perf record -e probe:vfs_read -aR sleep 1
>
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.048 MB perf.data (178 samples) ]
>
>
> From the perf report result I know two dso objects are leak:
>
> 90 probe_perf:dso__new `
> 88 probe_perf:dso__delete
>

The above result is gotten from yesterday's perf/core. I also tried
today's perf/core and get:

90 probe_perf:dso__new `
90 probe_perf:dso__delete

So we fix these leak.

Thank you.

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