krowitz@EDDIE.MIT.EDU@mit-kermit.UUCP (02/18/87)
I just installed SR9.5 on our network and began recompiling our
programs to take advantage of the new compilers which (it is
claimed) produce code that is significantly faster than the
old SR9.2 compilers produced. Just for fun I tried two of my
old favorites, the Whetstone and Linpack benchmarks. Here are
the results:
Whetstone (single) Whetstone (double)
------------------ ------------------
330 (SR9.2) 682 665
330 (SR9.5) 744 668
560 (SR9.2) 794 775
560 (SR9.5) 848 761
660 (SR9.2) 757 471
660 (SR9.5) 678 436
As you can see, the DN330 and DN560 got about 10% faster in
single precision, but had no increase in double precision. Even
more curiously, the DN660 got 10% slower in both single and
double precision. This is a performance enhancement? Why
would single precision get better and not double precision?
The story gets even worse when you look at the Linpack results:
Linpack (single) Linpack (double)
------------------ ------------------
330 (SR9.2) .072 .063
330 (SR9.5) .068 .060
560 (SR9.2) .079 .073
560 (SR9.5) .075 .068
660 (SR9.2) .102 .067
660 (SR9.5) .098 .061
In the case of Linpack, all nodes get 5% to 10% slower with
the new compilers. What is going on here? Have any other
sites using SR9.5 (or beta-testing it) found a real performance
gain?
-- David Krowitz
mit-erl!mit-kermit!krowitz@eddie.mit.edu
mit-erl!mit-kermit!krowitz@mit-eddie.arpa
david@mit-mc.arpa
(in order of decreasing preference)