linux-kernel - Re: [PATCH] perf tools: Synthesize anon MMAP records on the heap

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Message-ID: <CEFB09CC.2CAAA%gjain@fb.com>
Date:	Tue, 14 Jan 2014 20:48:23 +0000
From:	Gaurav Jain <gjain@...com>
To:	Don Zickus <dzickus@...hat.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arun Sharma <asharma@...com>
Subject: Re: [PATCH] perf tools: Synthesize anon MMAP records on the heap

On 1/13/14, 11:54 AM, "Don Zickus" <dzickus@...hat.com> wrote:

>On Sat, Jan 11, 2014 at 08:32:14PM -0800, Gaurav Jain wrote:
>> Anon records usually do not have the 'execname' entry. However if they
>>are on
>> the heap, the execname shows up as '[heap]'. The fix considers any
>>executable
>> entries in the map that do not have a name or are on the heap as anon
>>records
>> and sets the name to '//anon'.
>> 
>> This fixes JIT profiling for records on the heap.
>
>I guess I don't understand the need for this fix.  It seems breaking out
>//anon vs. [heap] would be useful.  Your patch is saying otherwise.  Can
>give a description of the problem you are trying to solve?

Thank you for looking at the patch.

We generate a perf map file which includes certain JIT¹ed functions that
show up as [heap] entries. As a result, I included the executable heap
entries as anon pages so that it would be handled in
util/map.c:map__new(). The alternative would be to handle heap entries in
map__new() directly, however I wasn¹t sure if this would break something
as it seems that heap and stack entries are expected to fail all
map__find_* functions. Thus I considered executable heap entries as
//anon, but perhaps there is a better way.

>Also style issue below..
>
>> 
>> Signed-off-by: Gaurav Jain <gjain@...com>
>> Cc: Ingo Molnar <mingo@...nel.org>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Paul Mackerras <paulus@...ba.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
>> Cc: Don Zickus <dzickus@...hat.com>
>> Cc: Arun Sharma <asharma@...com>
>> ---
>>  tools/perf/util/event.c | 5 ++---
>>  1 file changed, 2 insertions(+), 3 deletions(-)
>> 
>> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
>> index bb788c1..ae9c55b 100644
>> --- a/tools/perf/util/event.c
>> +++ b/tools/perf/util/event.c
>> @@ -224,10 +224,9 @@ static int
>>perf_event__synthesize_mmap_events(struct perf_tool *tool,
>>  				continue;
>>  
>>  			event->header.misc |= PERF_RECORD_MISC_MMAP_DATA;
>> -		}
>> -
>> -		if (!strcmp(execname, ""))
>> +		} if (!strcmp(execname, "") || !strcmp(execname, "[heap]")) {
>
>The '} if' part should seperate the 'if' on to its own line (unless you
>meant an 'else' in there).

Bah yes, I intended 'else if'. I apologize for that. Does the fact that I
filtered anon entries to only those marked as executable break the
existing behavior?

Thanks,

Gaurav

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