gcc and alphalinux
Tim.Tenhave at compaq.com
Thu May 25 09:35:03 PDT 2000
* Have you asked your questions to the peer-to-peer Compaq compiler support
program that is maintained by the folks from the University of New
* Here are some random thoughts from another engineer more familiar than I
on the EV5/56 compiler issues...
Differences in performance between Linux and Tru64 can be caused by
(1) gcc vs. ccc. This person has eliminated this difference by using
ccc on Linux.
(2) Compile switches. I recommend starting with "-O -fast" although
floating point intensive C programs might also like -O4.
(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
(4) Page coloring. The Tru64 kernel does this and Linux does not.
(5) Speculation. The Tru64 kernel supports this and Linux does not.
Hope this helps...
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