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From: Bruce Momjian on 3 Jul 2010 22:44
I have modified src/tools/test_fsync so its output is operations per
second, instead of total seconds, e.g.:

Loops = 10000

Simple write:
8k write 52549.436/second

Compare file sync methods using one write:
(open_datasync unavailable)
open_sync 8k write 575.599/second
(fdatasync unavailable)
8k write, fsync 349.669/second

Compare file sync methods using two writes:
(open_datasync unavailable)
2 open_sync 8k writes 215.472/second
(fdatasync unavailable)
8k write, 8k write, fsync 566.493/second

Compare open_sync with different sizes:
open_sync 16k write 247.207/second
2 open_sync 8k writes 219.824/second

Test if fsync on non-write file descriptor is honored:
(If the times are similar, fsync() can sync data written
on a different descriptor.)
8k write, fsync, close 719.469/second
8k write, close, fsync 1457.288/second

This should make the values more useful.

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

+ None of us is going to be here forever. +

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Prev: Why is vacuum_defer_cleanup_age PGC_USERSET?
Next: pessimal trivial-update performance