perf tip: fails to convert comm

[David Ahern <dsahern@gmail.com>]

Hi Namhyung and Frederic:

If you recall I mentioned noting a problem with the callchain series 
showing comm's. Well, it fails on acme's perf/core. git bisect points to:

$ git bisect bad
4dfced359fbc719a35527416f1b4b3999647f68b is the first bad commit
commit 4dfced359fbc719a35527416f1b4b3999647f68b
Author: Namhyung Kim <namhyung.kim@lge.com>
Date:   Fri Sep 13 16:28:57 2013 +0900

     perf tools: Get current comm instead of last one

     At insert time, a hist entry should reference comm at the time 
otherwise
     it'll get the last comm anyway.


How to re-create:

Start point is tools/perf directory for 3.12 (Linus tree):
   $ perf sched record -o /tmp/perf.data -g -- make -j 16
   $ perf script -i /tmp/perf.data > /tmp/1

cd to Arnaldo's tree, make perf and use it to create /tmp/2:
   $ perf script -i /tmp/perf.data > /tmp/1
   $ diff -U3 /tmp/1 /tmp/2 | less

You'll see a number of comm's showing as :<pid> instead of make, etc.

David