On 2013-12-05 11:15:20 +0200, Metin Doslu wrote: > > - When we increased NUM_BUFFER_PARTITIONS to 1024, this problem is > > disappeared for 8 core machines and come back with 16 core machines on > > Amazon EC2. Would it be related with PostgreSQL locking mechanism? > > If we build with -DLWLOCK_STATS to print locking stats from PostgreSQL, we > see tons of contention with default value of NUM_BUFFER_PARTITIONS which is > 16:
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Is your workload bigger than RAM? I think a good bit of the contention you're seeing in that listing is populating shared_buffers - and might actually vanish once you're halfway cached. >From what I've seen so far the bigger problem than contention in the lwlocks itself, is the spinlock protecting the lwlocks... Greetings, Andres Freund -- Andres Freund 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
