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cache alignment of tt

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Daniel Shawul

Joined: 14 Mar 2006
Posts: 2187
Location: Ethiopia

Post subject: Re: cache alignment of tt Posted: Sun Mar 11, 2012 11:06 pm

Quote:

Posted: Sun Mar 11, 2012 10:39 pm Post subject: Re: cache alignment of tt
Are you sure the alignment works on Windows? Whether your appliation runs faster is a CPU matter, and should not be affected by what OS you use.

I guess even a non-aligned malloc would be aligned on a 16-byte boundary, so that you dannot see an effect on the eval cache would be logical.

Yes it works. The alignment returned by malloc/new gurantees aligned access for the largest member variables (hashkey 8 byte), so I get multiples of 8. When I do alignement the remainder is 0 always. Also declaring some big tables like zobrist keys array and history table as cache aligned makes things slower on windows. I do not have a profiler there so I can not measure performance accurately.

Code:

template<typename T>
void aligned_reserve(T*& mem,const size_t& size) {
if((sizeof(T) & (sizeof(T) - 1)) == 0) {
#ifdef _MSC_VER
   mem = (T*)_aligned_recalloc(mem,size,sizeof(T),CACHE_LINE_SIZE);
#else
   if(mem) free(mem);
   posix_memalign((void**)&mem,CACHE_LINE_SIZE,size * sizeof(T));
   memset(mem,0,size * sizeof(T));
#endif
} else {
   if(mem) free(mem);
   mem = (T*) calloc(size,sizeof(T));
}
print("address %d remainder %d\n",(uintptr_t)mem,(uintptr_t)mem % 64);
}

After alignment for main & eval cache. Pawn cache has a size of 24 so I do not align it even though doing so should not hurt I think.

Code:

feature done=0
address 40697920 remainder 0
address 74317888 remainder 0
address 82772000 remainder 32
ht 1048576 X 64 = 64MB
eht 524288 X 16 = 8MB
pht 349525 X 24 = 7MB

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Display posts from previous:

Subject	Author	Date/Time
cache alignment of tt	Daniel Shawul	Sun Mar 11, 2012 10:22 pm
Re: cache alignment of tt	H.G.Muller	Sun Mar 11, 2012 10:39 pm
Re: cache alignment of tt	Daniel Shawul	Sun Mar 11, 2012 11:06 pm
Re: cache alignment of tt	Jon Dart	Mon Mar 12, 2012 12:43 am
Re: cache alignment of tt	Daniel Shawul	Mon Mar 12, 2012 2:53 am
Re: cache alignment of tt	Vincent Diepeveen	Thu Mar 15, 2012 8:12 pm
Re: cache alignment of tt	Robert Purves	Mon Mar 12, 2012 4:10 am
Re: cache alignment of tt	Daniel Shawul	Mon Mar 12, 2012 4:49 am
Re: cache alignment of tt	Robert Hyatt	Mon Mar 12, 2012 5:21 am
Re: cache alignment of tt	Ricardo Barreira	Mon Mar 12, 2012 8:25 am
Re: cache alignment of tt	Robert Hyatt	Mon Mar 12, 2012 3:54 pm
Re: cache alignment of tt	Alvaro Cardoso	Tue Mar 13, 2012 12:33 am
Re: cache alignment of tt	Robert Hyatt	Thu Mar 15, 2012 2:15 pm
Re: cache alignment of tt	Rémi Coulom	Thu Mar 15, 2012 4:42 pm
Re: cache alignment of tt	Robert Hyatt	Thu Mar 15, 2012 5:03 pm
Re: cache alignment of tt	Daniel Shawul	Thu Mar 15, 2012 5:08 pm
Re: cache alignment of tt	Daniel Shawul	Mon Mar 12, 2012 12:49 pm

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