Tom, > Strictly a WAG ... but what this sounds like to me is disastrously bad > behavior of the spinlock code under heavy contention. We thought we'd > fixed the spinlock code for SMP machines awhile ago, but maybe > hyperthreading opens some new vistas for misbehavior ...
Yeah, I thought of that based on the discussion on -Hackers. But we tried turning off hyperthreading, with no change in behavior. > If you can't try 7.4, or want to gather more data first, it would be > good to try to confirm or disprove the theory that the context switches > are coming from spinlock delays. If they are, they'd be coming from the > select() calls in s_lock() in s_lock.c. Can you strace or something to > see what kernel calls the context switches occur on? Might be worth it ... will suggest that. Will also try 7.4. -- -Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match