[Help-gsl] Speed problem

[Dirk Eddelbuettel]

On 25 May 2005 at 23:09, Jochen Küpper wrote:
| Paolo Zavarise <physics@paolo.zavarise.name> writes:
| 
| > GSL 1.6 compiled by myself is five/ten time slower than GSL included in 
| > ubuntu (1.5.90, same one I think). I've compiled with configure/make, no 
| > options, and installed in a non-default dir.

Is that a recompiled Ubuntu version, or the "straight" Debian package I
maintain?  In that case, the flags we use are 

DEB_BUILD_GNU_TYPE = $(shell dpkg-architecture -qDEB_BUILD_GNU_TYPE)
DEB_HOST_GNU_TYPE = $(shell dpkg-architecture -qDEB_HOST_GNU_TYPE)
ifneq ($(DEB_BUILD_GNU_TYPE),$(DEB_HOST_GNU_TYPE))
CONFARGS = --host=$(DEB_HOST_GNU_TYPE)
endif
[...]
compilerflags	= "-O2 -D_REENTRANT"
[...]
	./configure 	--prefix=/usr 		\
			--enable-shared 	\
			--enable-static 	\
			--with-gnu-ld 		\
			$(CONFARGS)
[...]
	$(MAKE)		CFLAGS=$(compilerflags)			

i.e. it is basically just doing a regular -O2. (-D_REENTRANT is mandated by
Debian Policy as it should make multi-threaded apps behave better, as I
recall, as has no performance implications.)

| Did you compile with optimizations? If not, try setting CFLAGS, i.e. 
| ,----
| | export CFLAGS="-g -O2 -pipe -Wall"
| `----
| Best would be to look at the GCC manual...

Also, what are you using as the benchmark, and how are you comparing this?
On a dual-boot system where you may have Atlas under Ubuntu but not on the
second system? Just a thought.

Dirk

-- 
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