Author: Tony Werten
Date: 08:06:08 12/01/03
Go up one level in this thread
On December 01, 2003 at 10:46:00, Robert Hyatt wrote: >On December 01, 2003 at 02:41:28, Tony Werten wrote: > >>When my masterthread is spinning, waiting for results from it's workers threads, >>how do I keep it from burning CPU time ? > >You have a couple of choices. But why is it important? You have two cpus. One >thread is doing something useful, the other is spinning. What is the problem? >The spinning thread has _zero_ effect on the running thread. IE in crafty I >have something like this: > >while (!work); I don't want to do it the way Crafty does :) ( Nothing personal) I have the idea I make the parallel search more effective if I let the splitpoint exist after splitting. So when I search with 1 thread, I split, create (pick) 2 new threads let the splitpoint sleep, and have the 2 new threads search. Tony > >work gets copied into cache. Until another thread writes to it, I spin on >local cache, no bus traffic whatsoever, and the instant I get work I start >to work on it the very next CPU cycle. If you block, you take a huge >performance hit to block and then unblock. > >> >>The apifunction sleep() doesn't some threadsafe, suspending the thread and >>having it resumed by the worker seems overly complicated. ( Accept maybe if I >>can use a callback function ) >> > >use a mutex-type lock that blocks when the lock is already set. Or if >using posix threads a "condition variable" will work better as multiple >threads can wait for the condition to be satisfied and all can proceed >when it is. But spinning is _the_ high-performance solution. > >IE I certainly hope you use spinlocks rather than blocking locks for >mutual exclusion/critical sections??? > > >>Any thoughts ? >> >>Tony
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