All, Through the User Concurrency Thread on -performance [1], Tom and Jignesh found that our proximate bottleneck on SMP multi-user scaling is clog_buffers. Increasing clog_buffers to 64 improved this scaling by 30% per Jignesh:
=================== 8.3+ HOT = did not defer more from 8.2 Numbers and hit the CLOG problem at 1100 users (instead of 1000 for 8.2) 8.3 + HOT + CLOG = Got a 1350 users peak of 137364 txn and it held steady till 1450 before it started dropping.. The Best 8.2 +CLOG patch is at 1250user at 128638 txn.. which at the same users in 8.3 did 131265.. So per user transactions also seems to have improved.. Good but roughly 2% at same user count.. But peak value in terms of scalability the improvement is 6.7% Pristine 8.2 could do about 950 users at 100828 txn: So at same user transactions 8.3+HOT+CLOG gives about 102058 txn = 1.2% while in terms of scalability throughput we get a huge boost of 36.2% So if we get the CLOG patch integrated in 8.3+HOT+CLOG release then overall the gain from our pristine 8.2.4 release will be about 36% out of the box .... =================== So: 1) Is there any potential negative impact to increasing the number of CLOG buffers? 2) Is this a small enough change that we can make it during beta? ---Josh [1] http://archives.postgresql.org/pgsql-performance/2007-07/msg00237.php -- Josh Berkus PostgreSQL @ Sun San Francisco ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
