Author: Robert Hyatt
Date: 18:40:38 03/17/05
Go up one level in this thread
On March 17, 2005 at 21:16:36, Dann Corbit wrote: >On March 17, 2005 at 17:07:15, Robert Hyatt wrote: > >>On March 17, 2005 at 14:47:24, Matthew Hull wrote: >> >>>I have two vanilla builds of GNUChess 5.07. One is in CYGWIN, the other in >>>Linux. Both are on x86 architecture. But each allocates hash memory in >>>different volumes. >>> >>>Example command: >>> >>>./gnuchess -s 10000000 >>> >>>On Cygwin, this allocates 393216K of hash memory. >>> >>>On Linux, it allocates 327680K >>> >>>What is the reason for this? >> >>Several possibilities. But first, have you started both programs without the -s >>option to see how big they are, then restarted both with the -s to see the >>difference? > >Some other likely differences: > >1. structure packing (since the hash table seems to be an 'entries' count if >the struct is aligned differently it will not be at all surprising if the same >count of structs has different sizes on two machines. > >2. memory page sizes are different (small differences will be explained this >way) On the PC the pagesize is 4K period. Unless you use the huge page-size which most operating systems do not use (4mb for intel, I think AMD opteron supports a 2M page size as well). I can't imagine anyone with a hash entry size that is not a multiple of 4/8, which would eliminate the packing issue on the X86 box...
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.