Re: gcc 3.4.3 performance problem illustrated

[Kenneth Massey]

Thanks - curious that you don't have the same issue.  Anyone else tried it on 
an AMD64?



Paul Pluzhnikov wrote:
> Kenneth Massey <kmassey@masseyratings.com> writes:
> 
> 
>>BTW, are there any tools to actually count cache misses?
> 
> 
>   valgrind --tool=cacheprof
>   tsprof (http://www.bitwagon.com)
> 
> 
>>1) is this observed only on AMD64, or also x86 ?
> 
> 
> On "Intel(R) Pentium(R) 4 CPU 1500MHz", compiled with 
> "-O3 -march=pentium4", my results are:
> 
> g++3.2.3: 2.03
> g++3.4.3: 2.19
> g++4.0.0: 2.15
> 
> On "Pentium III (Coppermine) 850MHz", compiled with -O3
> 
> g++2.95.3: 6.95
> g++3.2.3:  6.75
> g++3.4.3:  6.78
> g++4.0.0:  6.68
> 
> P.S. There is an off-by-one bug which actually causes this to crash
> when compiled with g++2.95:
> 
> 
>>  for (int i=0;i<=k;i++)
> 
> 
> Better make that "for (int i = 0; i < k; i++)"
> 
> Cheers,


-- 
Kenneth Massey
http://www.masseyratings.com