On Fri, Jul 15, 2011 at 6:33 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Jul 15, 2011, at 8:55 AM, Simon Riggs <si...@2ndquadrant.com> wrote: >>> The only difference is how bulk write operations are handled. As long >>> as we wake WALWriter before wal_buffers fills then we'll be good. >>> Wakeup once per wal buffer is too much. I agree we should measure this >>> to check how frequently wakeups are required for bulk ops. > >> Yeah. The trick is to get the wake-ups to be frequent enough without >> adding too much latency to the backends that have to perform them. Off-hand, >> I don't have a good feeling for how hard that will be. > > I'd say send the signal when wal buffers are more than X% full (maybe > half). The suggestion to send it when wrapping around at the end of the > array is not quite right, because that's an arbitrary condition that's > not related to how much work there is for the walwriter to do. It > should be cheap to check for this while advancing to a new wal buffer.
Yes, I was trying to go too simple. I think we need to put the calculation and SetLatch() after we release WALInsertLock, so as to avoid adding contention. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
