On Thu, Mar 18, 2004 at 03:34:21PM -0500, Bruce Momjian wrote:
> Kurt Roeckx wrote:
> > 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.
> > 
> Wow, your O_SYNC times are great.  Where can I buy some?  :-)
> Anyway, we do need to find a way to test this because obviously there is
> huge platform variability.

New results with version 1.8:

Simple write timing:
        write                    0.150613

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      9.170472
        write, close, fsync      8.851715

Compare one o_sync write to two:
        one 16k o_sync write     2.617860
        two 8k o_sync writes     2.563437

Compare file sync methods with one 8k write:
        (o_dsync unavailable)
        open o_sync, write       1.031721
        write, fdatasync        25.599010
        write, fsync,           26.192824

Compare file sync methods with 2 8k writes:
(The fastest should be used for wal_sync_method)
        (o_dsync unavailable)
        open o_sync, write       2.268718
        write, fdatasync        27.029396
        write, fsync,           27.399243

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