On Wed, Apr 16, 2014 at 6:25 PM, Merlin Moncure <mmonc...@gmail.com> wrote: > On Tue, Apr 15, 2014 at 11:27 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: >> >> Just to summarize you about the previous discussion and the >> improvements that we decided to do in this area based on feedback >> are as follows: >> >> 1. Bgwriter needs to be improved so that it can help in reducing >> usage count and finding next victim buffer (run the clock sweep >> and add buffers to the free list). >> 2. SetLatch for bgwriter (wakeup bgwriter) when elements in freelist >> are less. >> 3. Split the workdone globallock (Buffreelist) in StrategyGetBuffer >> (a spinlock for the freelist, and an lwlock for the clock sweep). >> Here we can try to make it lock free based on atomic ops as >> well. >> 4. Bgwriter needs to be more aggressive, logic based on which it >> calculates how many buffers it needs to process needs to be >> improved. >> 5. Contention around buffer mapping locks. >> 6. Cacheline bouncing around the buffer header spinlocks, is there >> anything we can do to reduce this? >> 7. Choose Optimistically used buffer in StrategyGetBuffer(). >> 8. Don't bump the usage count every time buffer is pinned. > > What about: 9. Don't wait on locked buffer in the clock sweep.
Right, I remember you have written patch for it, I think we should consider it along with point-6. In general, I think unless we first improve the situation for BufFreelistLock and eviction strategy, it might not show benefit. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
