Re: SX164 installation
On Wed, 16 Sep 1998, Bob McElrath wrote:
> On Wed, 16 Sep 1998, Ettore Aldrovandi wrote:
> > o compiled a few small test C and C++ programs, and egcs
> > seems to be OK. A project of mine is to port the CERNLIB
> > to this machine. I'm not a Fortran programmer, but my wife
> > does some number crunching, and I'm sure it will be
> > interesting to see how this little beast does.
>
> I've read in various places that the libm on linux/alpha sucks pretty hard,
> so that fortran benchmarks on DEC Unix vs. Linux always give the DEC Unix a
> factor of 2 favor or so. g77 should allow you to compile it
> straightforwardly though. The Wisconsin group uses alphas and DEC Unix for
> our CERNLIB programs (Aleph), and they run quite nicely. :)
It depends... transcendental functions (log, sin, exp, etc.) depend on
libm. The math library from glibc is notoriously slow on Alpha. Luckily
someone wrote a fast math library, libffm, which I've heard compares well
to the DU libm.
The rest of the performance gap is compiler optimizations. Gcc and egcs
do not optimize as aggressively as the DU compilers. However source
optimizations can narrow that gap too.
Jeff
Reply to: