Testing structure (was) Re: Allowing WAL fsync to be done via O_SYNC

Is someone able to put together a testing-type script or sequence so
people can run this on the various platforms and then report the
results?

For example, I can setup benchmarking, (or automated testing) on various
Solaris platforms to run overnight and report the results in the
morning.  I suspect that quite a few people can do similar.

Would this be a good thing for someone to spend some time and effort on,
in generating testing-type scripts/structures?  It might be a useful
tool to use in the future when making performance/related decisions like
this.

Regards and best wishes,

Justin Clift

Tom Lane wrote:
> 
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > I later read Vadim's comment that fsync() of two blocks may be faster
> > than two O_* writes, so I am now confused about the proper solution.
> > However, I think we need to pick one and make it invisible to the user.
> > Perhaps a compiler/config.h flag for testing would be a good solution.
> 
> I believe that we don't know enough yet to nail down a hard-wired
> decision.  Vadim's idea of preferring O_DSYNC if it appears to be
> different from O_SYNC is a good first cut, but I think we'd better make
> it possible to override that, at least for testing purposes.
> 
> So I think it should be configurable at *some* level.  I don't much care
> whether it's a config.h entry or a GUC variable.
> 
> But consider this: we'll be more likely to get some feedback from the
> field (allowing us to refine the policy in future releases) if it is a
> GUC variable.  Not many people will build two versions of the software,
> but people might take the trouble to play with a run-time configuration
> setting.
> 
>                         regards, tom lane
> 
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