[patch] pg_stat_lwlocks view - lwlocks statistics

Hi,    I was doing patch review for patch of "pg_stat_lwlocks view - lwlocks statistics".   https://commitfest.postgresql.org/action/patch_view?id=885
   The mail for the patch work is at: http://archives.postgresql.org/pgsql-hackers/2012-06/msg01518.php 
   Following the steps on http://wiki.postgresql.org/wiki/Reviewing_a_Patch, the review is below:
1. submission review  The patch is in standard git diff format.   The patch applies with git repo master branch, in commit 8a504a363925fc5c7af48cd723da3f7e4d7ba9e2.  I applied back the patch with command "patch -p1 <pg_stat_lwlocks_20120626.diff".  The patch applies back cleanly.   There is no test file or doc patch, as I didn't find any.
2. Usability Review  I run queries to select from pg_stat_lwlocks and function pg_stat_get_lwlocks(), and they return the same results. And after running select from pg_stat_reset_lwlocks(), all the data seems to reset. So the stats relation and functions are working. 
3. Code format  Looking at the patch file, the code format looks nice. Also some basic comments inside. 
About the code quality, performance review and further bebugging, I'm not sure how should I do the testing.... Any suggestion? 
Any comment?Thanks.
 Best RegardsHuang Qi VictorComputer Science of National University of Singapore