WIEN2k-FAQ: Compilation on IBM p630 systems
©2001 by P. Blaha, K. Schwarz and J. Luitz
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Problem: Optimization for IBM p630.
IBMs AIX operating system does not understand the "-f" option for the
Unix command "hostname". So you must change in
$WIENROOT/w2web, $WIENROOT/SRC_w2web/w2web and $WIENROOT/SRC_w2web/bin/w2web
the lines
hostname -f by hostname alone.
The following was advised by T.Andersen (thor@physik.uni-kl.de)
- ESSL 4.1 is about 5% faster than 3.3 in lapw1c.
- Compiler options are: -q64 -O5
- Linker options are: -q64 -O5 -qipa=missing=isolated -L../SRC_lib
-bmaxdata:0x80000000
- It is important (especially for lapw2c) to have the optimization
options in the linking process, too. lapw2c gains about 20% in speed
because of that.
- lapack_lapw is an exception. It has to be compiled with -O3,
otherwise an infinite loop arises in the function DLAMC2, and lapwso and
lapw1c never finishes.
- I have experimented with the qipa options, and none of those that are
not included in the -O5 optimization level seem to have any further
impact on speed.
Peter Blaha,