Neil Conway <[EMAIL PROTECTED]> wrote: > > The patch adds a new choice "open_direct" to wal_sync_method. > Have you looked at what the performance difference of this option is?
Yes, I've tested pgbench and dbt2 and their performances have improved. The two results are as follows: 1. pgbench -s 100 on one Pentium4, 1GB mem, 2 ATA disks, Linux 2.6.8 (attached image) tps | wal_sync_method -------+------------------------------------------------------- 147.0 | open_direct + write multipage (previous patch) 147.2 | open_direct (this patch) 109.9 | open_sync 2. dbt2 100WH on two opterons, 8GB mem, 12 SATA-RAID disks, Linux 2.4.20 tpm | wal_sync_method --------+------------------------------------------------------ 1183.9 | open_direct (this patch) 911.3 | fsync > http://www.mail-archive.com/pgsql-patches@postgresql.org/msg07186.html > Is this data still applicable to the revised patch? Direct-IO might be good on some machines, and bad on others. This data is another reason that I revised the patch; If you don't use open_direct, WAL writer behaves quite similarly to former. However, the performances did not go down at least on my benchmarks. I have no idea why the above data was bad... --- ITAGAKI Takahiro NTT Cyber Space Laboratories
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