| From: | Kurt Roeckx <Q(at)ping(dot)be> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>, pgsql-performance(at)postgresql(dot)org, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] fsync method checking |
| Date: | 2004-03-18 20:26:21 |
| Message-ID: | 20040318202621.GB8330@ping.be |
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| Lists: | pgsql-hackers pgsql-performance |
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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