scott.marlowe wrote:
> I was testing to get some idea of how to speed up the speed of pgbench 
> with IDE drives and the write caching turned off in Linux (i.e. hdparm -W0 
> /dev/hdx).
> The only parameter that seems to make a noticeable difference was setting 
> wal_sync_method = open_sync.  With it set to either fsync, or fdatasync, 
> the speed with pgbench -c 5 -t 1000 ran from 11 to 17 tps.  With open_sync 
> it jumped to the range of 45 to 52 tps.  with write cache on I was getting 
> 280 to 320 tps.  so, not instead of being 20 to 30 times slower, I'm only 
> about 5 times slower, much better.
> Now I'm off to start a "pgbench -c 10 -t 10000" and pull the power cord 
> and see if the data gets corrupted with write caching turned on, i.e. do 
> my hard drives have the ability to write at least some of their cache 
> during spin down.

Is this a reason we should switch to open_sync as a default, if it is
availble, rather than fsync?  I think we are doing a single write before
fsync a lot more often than we are doing multiple writes before fsync.

  Bruce Momjian                        |
  [EMAIL PROTECTED]               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ?


Reply via email to