I have a couple of questions regarding the use of GSL with ATLAS. I am
working on a dual Opteron running Suse 9.3 Pro. I installed GSL v1.6.5
from the Suse dvd. I downloaded and installed ATLAS 3.7.11. I wrote a
test code to do a QR decompostion with N=1000. I compiled with -O2 and
the following libs:
LDLIBS = -lgsl -lgslcblas -lm
and
LDLIBS = -L/usr/local/ATLAS/lib/Linux_HAMMER64SSE2_2 -lgsl -lptcblas
-latlas -lm -lpthread
1.) I get virtually no performance difference with either of the
above. The executable size goes way up to like 7 MB with the latter. I
have also tried the single-threaded version of ATLAS.
2.) Only 1 cpu is doing any work. Is that correct, even though I
compiled and linked in the threaded versions of ATLAS?
Here is the second issue: I installed ATLAS on another dual Opteron box
running SLES9. SLES9 does not include GSL as part of its distribution
so I downloaded and installed GSL 1.7 from the website. Problem is,
it's about 10x slower than my machine! I went so far as to copy
libgsl.so.0.7.0 and link libgsl.so.0 to it instead of 0.8.0, and I got
my missing factor of 10 back. Can anyone comment on that?
Thanks,
Joe
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