> >> This seems odd. As near as I can tell, O_SYNC is simply a command to do
> >> fsync implicitly during each write call. It cannot save any I/O unless
> >> I'm missing something significant. Where is the performance difference
> >> coming from?
>
> > Yes, odd, but sure very reproducible here.
>
> I tried this on HPUX 10.20, which has not only O_SYNC but also O_DSYNC
AIX has O_DSYNC (which is _FDATASYNC) too, but I assumed O_SYNC
would be more portable. Now we have two, maybe it is more widespread
than I thought.
> I attach my modified version of Andreas' program. Note I do
> not believe his assertion that close() implies fsync() --- on the machines I've
> used, it demonstrably does not sync.
Ok, I am not sure, but essentially do we need it to sync ? The OS sure isn't
supposed to notice after closing the file, that it ran out of disk space.
Andreas
