[patch] tuning gcc for Intel Core2

H. J. Lu hjl@lucon.org
Wed Nov 15 22:34:00 GMT 2006


On Wed, Nov 15, 2006 at 09:56:24PM +0100, Jan Hubicka wrote:
> Actually on Opteron the gcc benchmark also has problems with library
> calls to string functions (but other benchmarks improve), those are not
> as high as in your scores.  I am not quite sure if this is not an
> annomaly. SPECint is not really good benchmark for a string functions as
> only benchmark that do depend on them is GCC and VORTEX. In SPECfp
> mesa/aspi.  By effectivly making compiler to optimize out any library
> calls you throw away any posibility for optimized library version
> handling nicely the large blocks, so programs that do use them (such as
> X) slows down.

Agreed. That is reason why we excluded it in the first place.

> 
> Do you have any understanding what really happens to GCC to slow down as
> much?  (sorry I didn't had chance to read the full thread, but will do
> so tomorrow, so I am sorry if this was already explained)
> 

X86-64 memory functions in glibc aren't very good. AMD contributed
a set of x86-64 memory functions. I have been working on Intel
version. It is a long process :-(.


H.J.



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