Author: Ernst A. Heinz
Date: 06:10:01 11/24/98
Go up one level in this thread
On November 24, 1998 at 08:29:12, Robert Hyatt wrote: > > [...] > >2. In results obtained by me (crafty and Cray Blitz), Cilkchess, and others, >the typical overhead is 30% per processor. IE Crafty is about 1.7X faster on >two processors, about 2.4X faster on 3, about 3.1X faster on 4, and so forth, >thru 8 from personal testing, and thru 16 taking someone else's data. Bob, AFAIK your 30% overhead is only a good average approximation for lowly parallel searchers on SMPs with *physically* shared hash tables. For massively parallel searchers on machines with *physically* distributed memory I have not yet seen any experimental data that *conclusively* supports such high parallel efficiency. To the contrary, the only frank publications in this respect seem to be the articles by the "StarTech" and "StarSocrates" groups who admit to something like an application speedup of only 50-60 on a CM-5 with 512 CPUs which translates to a parallel efficiency of 10%-15% for their Jamboree search. Most other researchers who reported higher relative speedups for their massively parallel implementations on distributed-memory machines either failed to account for the increases in hash-table sizes or used horribly inefficient sequential implementations as their point of reference. =Ernst=
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.