Re: test_fsync open_sync test

Greg Smith wrote:
> Bruce Momjian wrote:
> > Is there a value to this test_fsync test?
> >
> >     Compare open_sync with different sizes:
> >     (This is designed to compare the cost of one large
> >     sync'ed write and two smaller sync'ed writes.)
> >             open_sync 16k write               242.563 ops/sec
> >             2 open_sync 8k writes             752.752 ops/sec
> >
> > It compares the cost of doing larger vs. two smaller open_sync writes.
> >   
> 
> Might be some value for determining things like what the optimal WAL 
> block size to use is.  All these tests are kind of hard to use 
> effectively still, I'm not sure if it's time to start trimming tests yet 
> until we've made more progress on interpreting results first.

FYI, I beefed up the testing for this in test_fsync:
Compare open_sync with different write sizes:(This is designed to compare the cost of writing 16kin different write
open_syncsizes.)         1 16k open_sync write            723.824 ops/sec         2  8k open_sync writes
347.979ops/sec         4  4k open_sync writes           215.114 ops/sec         8  2k open_sync writes
174.613ops/sec        16  1k open_sync writes            87.496 ops/sec
 

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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