Re: Log levels for checkpoint/bgwriter monitoring

On Fri, 9 Mar 2007, ITAGAKI Takahiro wrote:

> "Pinned" means bufHdr->refcount > 0 and you don't distinguish pinned or 
> recently-used (bufHdr->usage_count > 0) buffers in your patch.

Thank you, I will revise the terminology used accordingly.  I was using 
"pinned" as a shortcut for "will be ignored by skip_pinned" which was 
sloppy of me.  As I said, I was trying to show how the buffer cache looks 
from the perspective of the background writer, and therefore lumping them 
together because that's how SyncOneBuffer views them.  A buffer cache full 
of either type will be largely ignored by the LRU writer, and that's what 
I've been finding when running insert/update heavy workloads like pgbench.

If I might suggest a terminology change to avoid this confusion in the 
future, I'd like to rename the SyncOneBuffer "skip_pinned" parameter to 
something like "skip_active", which is closer to the real behavior.  I 
know Oracle refers to these as "hot" and "cold" LRU entries.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD