>I have run these tests on P5, P6, IBM RS6K, SGIs without any problems
>and any source code changes - the total source code size for tests 1
>to 3 is 675 lines C. I am kind of suspecting that the code generated
>by gcc (no f2c involved here) is plain wrong.
It's possible that gcc is the culprit; there are some other
possibilities as well:
o The machines you list above are all 32-bit machines. If you
have 32-bit dirty C code, it won't run correctly on Linux/Alpha
(or Digital UNIX, either).
o If your code explicitly messes around with denormalized
floating point, or depends upon IEEE-754 rounding modes,
your performance on Alpha (Linux or not) will not be as
good as you were expecting. In the case of Digital UNIX,
the code causes exceptions, and the kernel then does fixups.
The architecture specifies software completion (rather than
hardware) for exceptional cases.
o You might have a buggy version of f2c - I believe Jim Paradis
(The principal technical instigator of Linux/Alpha in Digital)
had to make some source changes to get it working when he
was messing with it recently (less than a month ago)
My memory recalls having to build some stuff (glibc?) with
the -mieee switch.
If you have found gcc/f2c bugs, they won't get fixed unless either you
fix them, or you report the bugs to the maintainer.
>My question simply is: is it worth shelling out two times the price
>of a P6-200 for an Alpha running linux - I could live with sub-
>standard performance for half a year or so until compilers got better -
>I can't live with the fact that programs I know run on many machines
>won't even run properly.
I'm admittedly biased toward you choosing Linux/Alpha, (Digital
Semiconductor pays me to help sell chips) but I _do_ believe that you
will see a variety of significant improvements in the compiler space
for Linux/Alpha within the next 6 to 8 months. g77 is being worked on,
people are finding and squishing alpha-specific bugs at a very high rate,
ELF is coming along nicely, more and more Alpha platforms are being
supported by Linux, etc.
Rick
Richard Gorton All standard disclaimers apply.
Alpha Migration Tools Projects: DECmigrate (mx), FreePort Express,
Digital Semiconductor Linux/Alpha
Digital Equipment Corporation
Reply-to: gorton@tallis.enet.dec.com