Re: [HACKERS] fsync method checking

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.

---------------------------------------------------------------------------

>
> 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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