On 2013-08-05 10:49:08 -0500, Merlin Moncure wrote: > optimization 4: remove free list lock (via Jeff Janes). This is the > other optimization: one backend will no longer be able to shut down > buffer allocation
I think splitting off the actual freelist checking into a spinlock makes quite a bit of sense. And I think a separate one should be used for the actual search for the clock sweep. I don't think the unlocked increment of nextVictimBuffer is a good idea though. nextVictimBuffer jumping over NBuffers under concurrency seems like a recipe for disaster to me. At the very, very least it will need a good wad of comments explaining what it means and how you're allowed to use it. The current way will lead to at least bgwriter accessing a nonexistant/out of bounds buffer via StrategySyncStart(). Possibly it won't even save that much, it might just increase the contention on the buffer header spinlock's cacheline. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
