Re: Allowing WAL fsync to be done via O_SYNC

* Larry Rosenman <ler(at)lerctr(dot)org> [010318 14:17] wrote:
> * Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> [010318 14:55]:
> > Alfred Perlstein <bright(at)wintelcom(dot)net> writes:
> > >> Just by making a thread call libc changes personality to use thread
> > >> safe routines (I.E. add mutex locking). Use one thread feature, get
> > >> the whole set...which may not be that bad.
> >
> > > Actually it can be pretty bad. Locked bus cycles needed for mutex
> > > operations are very, very expensive, not something you want to do
> > > unless you really really need to do it.
> >
> > It'd be interesting to try to get some numbers about the actual cost
> > of using a thread-aware libc, on platforms where there's a difference.
> > Shouldn't be that hard to build a postgres executable with the proper
> > library and run some benchmarks ... anyone care to try?
> I can get the code compiled, but don't have the skills to generate
> a test case worthy of anything....

There's a 'make test' or something ('regression' maybe?) target that
runs a suite of tests on the database, you could use that as a
bench/timer, you could also try mysql's "crashme" script.

--
-Alfred Perlstein - [bright(at)wintelcom(dot)net|alfred(at)freebsd(dot)org]