Re: [R] Performance difference between 32-bit build and 64-bit bu ild on Solaris 8

From: Scott Gilpin <sgilpin_at_gmail.com>
Date: Sun 12 Jun 2005 - 04:13:20 EST

Andy, Prof. Ripley - thanks for your replies.

> CFLAGS was not specified, so should default to "-g -O2". It is definitely
> worth checking, although almost all the time in these tests will be spent
> in Fortran code.
Yes - I verified that's the default.

> >> neither build uses a BLAS.
>
> Well, they do, the one supplied with R (which is in Fortran).

I guess I should have said that neither build is using an optimized BLAS. (which I am planning to install - I just haven't had the chance yet.) I also get a message in config.log "ld: fatal: library -lblas: not found". I need to investigate this more.

> and for gcc 3.4.3 and the internal BLAS (which I had to build for these
> tests) I get
>
> 32-bit
> [1] 9.96 0.09 10.12 0.00 0.00
> 64-bit
> [1] 9.93 0.04 10.04 0.00 0.00
>
> so I am not seeing anything like the same performance difference between
> 32- and 64-bit builds (but it could well depend on the particular Sparc
> chip).

These timings are much, much less than what I reported (~700s and 2200s for 32 bit and 64 bit). I read the admin manual and didn't see anything specifically that needs to be set to use the internal BLAS. I guess I'll go back and do some more investigation.

Thanks for your help.



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