Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: odd multithreaded search behavior--explanation?

Author: Tom Kerrigan

Date: 00:48:53 05/26/00

Go up one level in this thread


On May 26, 2000 at 03:38:35, Jeremiah Penery wrote:

>On May 26, 2000 at 02:49:55, Tom Kerrigan wrote:
>
>>I've been writing a multithreaded program. I'm running on 1 processor but my
>>program splits into 4 threads. So far, the threads don't communicate in any way,
>>so searches take exactly 4 times as long (not counting some overhead).
>>
>>But this evening I added a shared hash table,
>
>
>>and now the threads=4 program is
>>only slightly slower (in terms of NPS and nodes/ply) than the threads=1 >program.
>>
>>Is this some sort of mistake? I tried for almost an hour to prove that >something
>>flakey is going on, but it seems to really go 4 times faster
>
>Do you mean it's slower in terms of NPS, but faster in terms of
>solution/iteration time?

I mean when I have threads=4, the hash table makes the program ~4 times faster.

Hopefully I can find an actual MP computer to run on in the next week or so, to
see if this result is a fluke.

-Tom



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.