Re: test_fsync label adjustments

On Jan 18, 2011, at 3:55 PM, Bruce Momjian wrote:

> I have modified test_fsync to use test labels that match wal_sync_method
> values, and and added more tests for open_sync with different sizes.
> This should make the program easier for novices to understand. Here is
> a test run for Ubuntu 11.04:
>
> $ ./test_fsync
> 2000 operations per test
>
> Compare file sync methods using one 8k write:
> (in wal_sync_method preference order, except fdatasync
> is Linux's default)
> open_datasync (non-direct I/O)* 85.127 ops/sec
> open_datasync (direct I/O) 87.119 ops/sec
> fdatasync 81.006 ops/sec
> fsync 82.621 ops/sec
> fsync_writethrough n/a
> open_sync (non-direct I/O)* 84.412 ops/sec
> open_sync (direct I/O) 91.006 ops/sec
> * This non-direct I/O mode is not used by Postgres.

I am curious how this is targeted at novices. A naive user might enable the "fastest" option which could be exactly wrong. For this to be useful to novices, I suspect the tool will need to generate platform-specific suggestions, no?

Cheers,
M