On Thu, Nov 15, 2012 at 2:20 PM, Vlad <marchenko@xxxxxxxxx> wrote: > Merlin, > > this is not my report, probably from a thread that I've referenced as having > a common symptoms. Here is info about my db: > > > Postgresql 9.1.6. > Postgres usually has 400-500 connected clients, most of them are idle. > Database is over 1000 tables (across 5 namespaces), taking ~150Gb on disk. > We have mostly select statements (joins across few tables), using indexes > and resulting in a small number of records returned. > > So mostly small lookups across few tables joining by a primary key / index. > Also, I just perform an experiment - I switched our app over to using hot > PITR instead of master and it experienced the same problem. So since PITR db > can only perform read-only queries, there is no write-locks (except maybe > when pitr is playing wal records from the master?), nevertheless SYS CPU > jumped sky. yeah. ok, nest steps: *) can you confirm that postgres process is using high cpu (according to top) during stall time *) if, so, please strace that process and save some of the log *) you're using a 'bleeding edge' kernel. so we must be suspicious of a regression there, particularly in the scheduler. *) I am suspicious of spinlock issue. so, if we can't isolate the problem, is running a hand complied postgres a possibility (for lock stats)? *) what is the output of this: echo /proc/sys/vm/zone_reclaim_mode merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
