Sorry for the late reply.! Ok, I understand. Thanks for the explanation !
Riccardo On Jan 3, 2008 12:57 PM, Brian Gough <[EMAIL PROTECTED]> wrote: > At Wed, 2 Jan 2008 15:44:40 +0100, > Riccardo Lucchese wrote: > > Anyway on calls like ddot this can be 2 times faster than now, and > > as in my tests simple functions like ddot don't take any advantage > > in using sse ecc.. (especially due to the calls overhead). > > > > Maybe I'm all wrong :) ? Any other ideas? > > To do the equivalent of 'NOSIZECHECK' I would call the cblas_ routines > directly, instead of the gsl_blas routines. This will eliminate the > size-checking overhead. > > If function call overhead is still a problem (i.e. 'FORCEINLINE') then > your vectors must be quite small, otherwise the computation of the > BLAS routine itself will dominate. > > BLAS was really designed for large vectors. In the small vector case > some equivalent inline functions could help. James Bergstra wrote > some sample inline BLAS routines a while back but I believe he decided > they did not give enough performance advantage unless the vector was > extremely small (like a few elements). I think there could be some > cases (like DDOT as you say) where it could be worthwhile though. It > would make sense to write such functions as an alternative to any > cblas_ library. > > With small vectors one is usually working with a fixed rather than > variable length, which is another distinction from the usual BLAS > routines. > > -- > Brian Gough > > Network Theory Ltd, > Publishing Free Software Manuals --- http://www.network-theory.co.uk/ > > _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
