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

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Date:	Wed, 15 Jan 2014 06:44:39 +0000
From:	Gaurav Jain <gjain@...com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Don Zickus <dzickus@...hat.com>,
	"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

Hi Namhyung,


On 1/15/14, 12:46 AM, "Namhyung Kim" <namhyung@...nel.org> wrote:

>I'd like to take my ack back - it seems I missed some points.

No worries, looks like the patch wasn’t well thought out.

>On Tue, 14 Jan 2014 20:48:23 +0000, Gaurav Jain wrote:
>> 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.
>
>Hmm.. so the point is that an executable heap mapping should have
>/tmp/perf-XXX.map as a file name, right?  If so, does something like
>below work well for you?

Just gave it a try and it fixed the issue perfectly! Thanks for the help.
This looks like a much better solution than treating the heap mapping as
an anon record.

Gaurav

>diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
>index 9b9bd719aa19..d52387fe83f1 100644
>--- a/tools/perf/util/map.c
>+++ b/tools/perf/util/map.c
>@@ -69,7 +69,7 @@ struct map *map__new(struct list_head *dsos__list, u64
>start, u64 len,
> 		map->ino = ino;
> 		map->ino_generation = ino_gen;
> 
>-		if (anon) {
>+		if (anon || (no_dso && type == MAP__FUNCTION)) {
> 			snprintf(newfilename, sizeof(newfilename), "/tmp/perf-%d.map", pid);
> 			filename = newfilename;
> 		}
>@@ -93,7 +93,7 @@ struct map *map__new(struct list_head *dsos__list, u64
>start, u64 len,
> 			 * functions still return NULL, and we avoid the
> 			 * unnecessary map__load warning.
> 			 */
>-			if (no_dso)
>+			if (no_dso && type != MAP__FUNCTION)
> 				dso__set_loaded(dso, map->type);
> 		}
> 	}