On Tue, Jan 14, 2014 at 1:37 PM, Jan Kara <j...@suse.cz> wrote: > Just to get some idea about the sizes - how large are the checkpoints we > are talking about that cause IO stalls?
Big. Potentially, we might have dirtied all of shared_buffers and then started evicting pages from there to the OS buffer pool and dirties as much memory as the OS will allow, and then the OS might have started writeback and filled up all the downstream caches between the OS and the disk. And then just then the checkpoint hits. I dunno what a typical checkpoint size is but I don't think you'll be exaggerating much if you imagine that everything that could possibly be dirty is. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
