I have updated my program with your suggested changes and put in
src/tools/fsync. Please see how you like it.
---------------------------------------------------------------------------
Zeugswetter Andreas SB SD wrote:
>
> > Running the attached test program shows on BSD/OS 4.3:
> >
> > write 0.000360
> > write & fsync 0.001391
>
> I think the "write & fsync" pays for the previous "write" test (same filename).
>
> > write, close & fsync 0.001308
> > open o_fsync, write 0.000924
>
> I have tried to modify the program to more closely resemble WAL
> writes (all writes to WAL are 8k), the file is usually already open,
> and test larger (16k) transactions.
>
> zeu@a82101002:~> test_sync1
> write 0.000625
> write & fsync 0.016748
> write & fdatasync 0.006650
> write, close & fsync 0.017084
> write, close & fdatasync 0.006890
> open o_dsync, write 0.015997
> open o_dsync, one write 0.007128
>
> For the last line xlog.c would need to be modified, but the measurements
> seem to imply that it is only worth it on platforms that have O_DSYNC
> but not fdatasync.
>
> Andreas
Content-Description: test_sync1.c
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