Here are my results on Linux 2.6.1 using cvs version 1.7.
Those times with > 20 seconds, you really hear the disk go crazy.
And I have the feeling something must be wrong. Those results
are reproducible.
Kurt
Simple write timing:
write 0.139558
Compare fsync times on write() and non-write() descriptor:
(If the times are similar, fsync() can sync data written
on a different descriptor.)
write, fsync, close 8.249364
write, close, fsync 8.356813
Compare one o_sync write to two:
one 16k o_sync write 28.487650
two 8k o_sync writes 2.310304
Compare file sync methods with one 8k write:
(o_dsync unavailable)
open o_sync, write 1.010688
write, fdatasync 25.109604
write, fsync, 26.051218
Compare file sync methods with 2 8k writes:
(The fastest should be used for wal_sync_method)
(o_dsync unavailable)
open o_sync, write 2.212223
write, fdatasync 27.439907
write, fsync, 27.772294
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