gcc and alphalinux

[Tenhave, Tim]

>
> (2) Compile switches. I recommend starting with "-O -fast" although
>
> floating point intensive C programs might also like -O4.
>

I have looked into using switches and this does increase my speed, but I am
still approximenly 30% off those codes compiled on the digital unix machine.

>
> (3) Prefetching. The compilers on Linux do not do this because of a
>
> bug in the Linux MILO PALcode for EV-5 and EV-56 systems. If the
>
> customer had an EV-6 based Linux cluster then using "-arch ev6" will
>
> turn on prefetching because the Linux PALcode bug does not occur on
>
> EV--6 system.
>
> (4) Page coloring. The Tru64 kernel does this and Linux does not.
>
> (5) Speculation. The Tru64 kernel supports this and Linux does not.
>
>

************

Tim:  I think these things above and some Tru64 linker optimizations are at
play
with your difference in performance.  Please realize I am a Beowulf
Systems/software
engineer, not one of the compiler folks.  

************

This leads me to my next question.  Are there any legal implications to
compiling binaries utilizing the digital unix environment and then running
those binaries on the linux machine?  (we have licenses for digital unix on
each of the nodes, although we will be running linux).  If this is the case,
then I have solved my problem .)

**************

Tim: I am not a lawyer (nor do I want to be one) and I would do what works.


So, let me refer you to a couple of similar issues and I will let you
decide:

http://www.alphalinux.org/docs/netscape_du.shtml -- check out the first
paragraph.

http://www.alphalinux.org/archives/axp-list/1996/February1996/0029.html

http://www.alphalinux.org/archives/axp-list/1996/February1996/0031.html