Author: Robert Hyatt
Date: 07:07:10 10/01/04
Go up one level in this thread
On October 01, 2004 at 01:10:39, Tony Werten wrote:
>Hi all,
>
>I have a simple question on wich I thought I had an answer, but I'm starting to
>doubt. However, since the memory requirements of my program are still getting
>bigger very fast, I'm not sure what is to blame, and switching back and forth
>takes too much time.
>
>Question:
>
>What is faster ?
>
>struct
>{
> move current_move[MAXPLY],hashmove[MAXPLY],killers[MAXPLY];
>
> moves movelist[3000]
> // etc
>
>} TREE
>
>or
>
>struct
>{
> move current_move,hashmove,killers;
> // etc
>
>} SEARCHDATA
>
>struct
>{
> SEARCHDATA data[MAXPLY];
>
> moves movelist[3000]
> //
>
>} TREE
>
>ie In the second case, all data from current ply should be close in memory and I
>can locally use a SEARCHDATA* wich would be pointing to
> &tree.data[currentply], and have less adresscalculation.
>
>I always thought the 2nd should be fastest. Is that so ?
>
>Tony
The way to answer this is to study temporal locality for the variables.
Variables that are used close together in terms of time should be close together
in memory. In the above I really don't see why they would be any different,
since the memory layout should be the same if I am looking at it correctly. IE
the current_move, hash_move and killer_move arrays are adjacent in memory in
either, followed by the movelist. It might be minimally faster to make a
structure with a single hash_move, killer_move and current_move in it, and use
that to define an array. Then the data for each ply would be in adjacent memory
words and get pre-fetched properly.
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