Author: Tom Kerrigan
Date: 23:49:55 05/25/00
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, even though the threads don't communicate (except for the hash table). The PVs and scores that the programs spit out are exactly the same, and the threads seem to be sharing the work equally. Could this be some sort of side effect from running on 1 processor? Thanks for any comments. -Tom
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