Details about pg_stat_bgwriter

Hi,

I'm trying to understand the information shown in pg_stat_bgwriter.

If I want to identify a possible bottleneck with the bgwriter, for what kind of numbers do I need to watch out?

Are the following values OK, or do they indicate that I need to tune my configuration?

checkpoints_timed  : 6099
checkpoints_req    : 291
buffers_checkpoint : 2767641
buffers_clean      : 4522
maxwritten_clean   : 1
buffers_backend    : 609933
buffers_alloc      : 1411947

I have read Greg's description (http://www.westnet.com/~gsmith/content/postgresql/chkp-bgw-83.htm), but to be honest I
don'tunderstand the explanation. He mentions a "LRU background writer", but I'm not sure to which column that relates. 

Thanks in advance.
Thomas