Author: Vincent Diepeveen
Date: 04:48:12 09/25/02
Hello, I'm looking to a quick alternative for the windows function WaitForSingleObject(); It waits until it gets signaled or times out after xx milliseconds. I go use it for the i/o thread which is supposed to sit idle till the end of a ply or till it checks for input or the clock. I remember for unix something about select and such but i completely lost that code. Also i want to know what speed it runs at. Because the first 10 ply or so which get out of hashtable with 40 legal moves, it is done instantly after a ply starts, and obviously it means that i need to do this 400 times instantly after a search starts. i don't want to wait real long there for just the first few ply! The second thing i sit with is that all processes at start of the search need to sit idle till they get a job. Previously what i did was letting them spin. That's pretty impossible. Under Irix i'm using spin_lock() here. It suspends processes when it can't lock in. Select and such i never managed to figure out and most likely signalling interprocessor is pretty hard and manual page of irix says that select only goes till 128 processors anyway. Partitions bigger than that it doesn't work simply. So where spin_lock is an idea for irix, i might guess WaitforSingleObject is working for windows (better alternatives i have an open mind for too) and it's a mystery to me what to use under linux. The problem is i can't use pthread_cond_wait, because it's not only an i/o thread that has to get signalled, but several other processes must be able to do it too... I asked SGI and they had no good alternative for me apart from the existing spin_lock which i already use and usema. So i guess i go do it with spin_lock() there. Basically the machine is ideal for multiprocessing, but amazingly there is not much info about it, like most OSes they focussed even more upon multithreading (which i find a wrong approach, BOTH should get attention). usema is something i will try if spin_lock() doesn't work out well. Best Regards, Vincent
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