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 16k
in different write open_sync sizes.)
1 16k open_sync write 723.824 ops/sec
2 8k open_sync writes 347.979 ops/sec
4 4k open_sync writes 215.114 ops/sec
8 2k open_sync writes 174.613 ops/sec
16 1k open_sync writes 87.496 ops/sec

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +