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

> 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

<<attachment: pgbench-result.png>>

---------------------------(end of broadcast)---------------------------
TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]

Reply via email to