On Sun, Jun 12, 2011 at 10:39 PM, Robert Haas <robertmh...@gmail.com> wrote: > I hacked up the system to > report how often each lwlock spinlock exceeded spins_per_delay.
I don't doubt the rest of your analysis but one thing to note, number of spins on a spinlock is not the same as the amount of time spent waiting for it. When there's contention on a spinlock the actual test-and-set instruction ends up taking a long time while cache lines are copied around. In theory you could have processes spending an inordinate amount of time waiting on a spinlock even though they never actually hit spins_per_delay or you could have processes that quickly exceed spins_per_delay. I think in practice the results are the same because the code the spinlocks protect is always short so it's hard to get the second case on a multi-core box without actually having contention anyways. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
