At 2014-11-26 18:56:52 -0500, br...@momjian.us wrote: > > I would test it with fsync=off to remove the fsync delay. That will > simulate an SSD or BBU controller.
The earlier tests were run with fsync=off. I ran another round of the replay tests on the i7 server, this time replaying 30GB of WAL segments. master 16:08:03 16:16:23 08:20 16:19:33 16:28:03 08:30 16:32:20 16:41:17 08:57 16:42:42 16:51:22 08:40 8crc 16:52:11 16:59:48 07:37 17:01:07 17:08:30 07:23 17:22:16 17:30:11 07:55 17:31:29 17:39:06 07:37 These are just the results of the last four runs with each branch, but the difference was consistent over many more runs. To summarise: the slice-by-8 patch (a) increases pure CRC performance by a large margin, (b) has a positive effect on reading WAL during replay, (c) doesn't hurt XLogInsert in typical cases (which was the main worry). -- Abhijit -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers