| Re: [eigen] Performance gap between gcc and msvc ? |
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I've checked with icc, it does the computation in 11s...
For comparaison, I can do a 4096x4096 qr reduction (double) in less than
16 sec with gcc and icc on a core2 quad.
It seems to be a bug related with core i5 and linux, maybe only under
openSuse 11.3. I may try with ubuntu in a near future.
On Sun, 20 Jun 2010 10:34:18 -0400, Benoit Jacob
<jacob.benoit.1@xxxxxxxxx>
wrote:
> forgot to reply earlier, but thanks a lot for the code, that can come in
> handy!
>
>
> 2010/6/18 Thomas Capricelli <orzel@xxxxxxxxxxxxxxx>:
>>
>> If that might help, I use the following code in one of my project to
get
>> a working 'cpuid' across compilers:
>> (inside a proper #ifdef for x86/amd64, of course):
>>
>> #if defined(__GNUC__)
>> # if defined(__PIC__) && defined(__i386__)
>> # define cpuid(abcd,func) \
>> __asm__ __volatile__ ("xchgl %%ebx, %%esi;cpuid; xchgl
>> %%ebx,%%esi": "=a" (abcd[0]), "=S" (abcd[1]), "=c" (abcd[2]), "=d"
>> (abcd[3]) : "a" (func));
>> # else
>> # define cpuid(abcd,func) \
>> __asm__ __volatile__ ("cpuid": "=a" (abcd[0]), "=b" (abcd[1]),
>> "=c" (abcd[2]), "=d" (abcd[3]) : "a" (func) );
>> # endif
>> #elif defined(_MSC_VER)
>> # define cpuid(abcd,func) __cpuid((int*)abcd,func)
>> #endif
>>
>> #ifndef cpuid
>> #error "Failed to find a way to get cpuid() for this architecture."
>> #endif
>>
>> (and wikipedia describes what you can get, very useful :-)
>>
>> Thomas
>> --
>> Thomas Capricelli <orzel@xxxxxxxxxxxxxxx>
>> http://www.freehackers.org/thomas
>>
>> In data venerdì 18 giugno 2010 23:42:50, Benoit Jacob ha scritto:
>>> ok, looks what we need is just the CPUID instruction.
>>>
>>>
http://en.wikipedia.org/wiki/CPUID#EAX.3D2:_Cache_and_TLB_Descriptor_information
>>>
>>> apparently this is what linux uses for /proc/cpuinfo.
>>
>>
>>