linux-kernel - Re: [PATCH 1/8] perf tools: Omit DWARF judgement when recording dwarf callchain

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Message-ID: <57313D10.5040808@huawei.com>
Date:	Tue, 10 May 2016 09:44:48 +0800
From:	Hekuang <hekuang@...wei.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>
CC:	<peterz@...radead.org>, <mingo@...hat.com>,
	<alexander.shishkin@...ux.intel.com>, <wangnan0@...wei.com>,
	<jpoimboe@...hat.com>, <ak@...ux.intel.com>, <eranian@...gle.com>,
	<namhyung@...nel.org>, <adrian.hunter@...el.com>,
	<sukadev@...ux.vnet.ibm.com>, <masami.hiramatsu.pt@...achi.com>,
	<tumanova@...ux.vnet.ibm.com>, <kan.liang@...el.com>,
	<penberg@...nel.org>, <dsahern@...il.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/8] perf tools: Omit DWARF judgement when recording dwarf
 callchain

ok

在 2016/5/10 0:16, Arnaldo Carvalho de Melo 写道:
> Em Sat, May 07, 2016 at 08:03:46PM +0200, Jiri Olsa escreveu:
>> On Fri, May 06, 2016 at 08:59:07AM +0000, He Kuang wrote:
>>> There's no need for dwarf support when perf recording with callchain.
>>>
>>> Signed-off-by: He Kuang <hekuang@...wei.com>
>> Acked-by: Jiri Olsa <jolsa@...nel.org>
> Ok, due to your Ack I went on to read the code and indeed, with this
> changeset description:
>
> "There is no need to check for DWARF unwinding support when using the
> 'dwarf' callchain record method, as this will only ask the kernel to
> collect stack dumps for later DWARF CFI processing, which can be done
> in another machine, where the support for DWARF unwinding need to be
> present."
>
> Thanks,
>
> - Arnaldo
>   
>> thanks,
>> jirka
>>
>>> ---
>>>   tools/perf/util/util.c | 2 --
>>>   1 file changed, 2 deletions(-)
>>>
>>> diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
>>> index b7766c5..e5ebfd4 100644
>>> --- a/tools/perf/util/util.c
>>> +++ b/tools/perf/util/util.c
>>> @@ -471,7 +471,6 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
>>>   				       "needed for --call-graph fp\n");
>>>   			break;
>>>   
>>> -#ifdef HAVE_DWARF_UNWIND_SUPPORT
>>>   		/* Dwarf style */
>>>   		} else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
>>>   			const unsigned long default_stack_dump_size = 8192;
>>> @@ -487,7 +486,6 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
>>>   				ret = get_stack_size(tok, &size);
>>>   				param->dump_size = size;
>>>   			}
>>> -#endif /* HAVE_DWARF_UNWIND_SUPPORT */
>>>   		} else if (!strncmp(name, "lbr", sizeof("lbr"))) {
>>>   			if (!strtok_r(NULL, ",", &saveptr)) {
>>>   				param->record_mode = CALLCHAIN_LBR;
>>> -- 
>>> 1.8.5.2
>>>