linux-kernel - Re: Does perf inject preserve call chain data?

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Date:	Mon, 11 Jun 2012 12:23:46 -0600
From:	David Ahern <dsahern@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC:	Tim Chen <tim.c.chen@...ux.intel.com>,
	linux-kernel <linux-kernel@...r.kernel.org>, ak@...ux.intel.com,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: Does perf inject preserve call chain data?

On 6/8/12 11:17 AM, Tim Chen wrote:
> On Fri, 2012-06-08 at 11:13 -0600, David Ahern wrote:
>> On 6/8/12 10:44 AM, Tim Chen wrote:
>>> On Fri, 2012-06-08 at 11:38 -0300, Arnaldo Carvalho de Melo wrote:
>>>> Em Tue, May 22, 2012 at 03:58:40PM -0600, David Ahern escreveu:
>>>>> On 5/22/12 12:49 PM, Tim Chen wrote:
>>>>>> Arnaldo,
>>>>>>
>>>>>> Wonder if perf inject munged the call chain data from perf record?
>>>>>>
>>>>>> When I do
>>>>>> perf record -a -g -o - sleep 5 |perf inject -v -b  | perf report  -g -i -
>>>>>> I get a complain from perf report
>>>>>>
>>>>>> Warning:
>>>>>> Selected -g but no callchain data. Did you call 'perf record' without -g?
>>>>>>
>>>>>
>>>>> I believe the root cause is that the event list is not written to
>>>>> the pipe. Using Arnaldo's git repo as of today (has fixes from
>>>>> Stephane) this hack shows the info is there and can be processed.
>>>>
>>>> How things stand here? Tim, did this fix things for you? If so, David,
>>>> please resend with a proper subject line and a Tested-by: Tim, ok?

Pipeline is broken by this commit in your urgent (but not yet pushed) tree:

commit 47832ad3e101e470a90fab9b4915549aaee03662
Author: Dmitry Antipov <dmitry.antipov@...aro.org>
Date:   Fri Jun 8 16:23:27 2012 +0400

     perf report: Fix event name reporting in cross analysis

     Use trace_find_event to find event name before looking through /sys
     files. This helps 'perf report' to show real event names instead of
     'unknown:unknown' when processing perf.data recorded on another 
machine.


pevent might be NULL and pevent_find_event dereferences it causing a crash.

David
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