Author: Tony Werten
Date: 00:41:08 09/05/03
Go up one level in this thread
On September 04, 2003 at 11:10:36, Robert Hyatt wrote: >On September 04, 2003 at 04:54:53, Tony Werten wrote: > >>On September 03, 2003 at 10:44:11, Sune Fischer wrote: >> >>>On September 03, 2003 at 10:35:11, Gian-Carlo Pascutto wrote: >>> >>>>On September 03, 2003 at 10:26:19, Sune Fischer wrote: >>>> >>>>>>What is your point? >>>>> >>>>>Heh :) >>>>> >>>>>You said (remote) checking for fail_high conditions at every node was required, >>>>>and I disagree. >>>> >>>>I never say 'at every node'. >>> >>>You said constantly, then I don't know what you mean by that. >>> >>>>Each time you get a subtree score, you must send out the score update to >>>>all processors, or store it locally and rely on remote processors to check >>>>it in your memory. >>>> >>>>Either way, you need remote accesses. >>>> >>>>Got it now? >>> >>>This is an entirely different matter, you don't get subtree scores "constantly". >>> >>>And I still say you only have to access when there is something to communicate. >>> >>>If you just quietly exit the subtree on a fail low, I see no need for >>>communication. >> >>I suddenly see the point you're missing. What you describe works correct on a >>dual machine only. >> >>Think about a 4 processor machine. >> >>processor 1 and 2 are running. >> >>processor 3 runs and starts a new thread on proc. 4 >> >>Now proc 4 is done, proc 3 get's this (ie he get's a done message, with score ) >> >>But how are proc 1 and 2 going to know that 4 is available ? >> >>Tony > >Lock(); >idle++; >Unlock(); > >and that does it. _everybody_ can see "idle" (which is zero 99.9999% of the >time since processors are not idle that often). The value is in local cache, >it costs nothing to test frequently, until a cache snoop discovers the valueeeee >has been changed. :) sometimes things are easy. Tony > >The lock can be eliminated if desired, by using a somewhat different meaning for >"idle". > >> >>> >>>-S. >>>>-- >>>>GCP
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