jcduell_at_lbl_dot_gov
Date: Tue Nov 29 2005 - 22:14:41 PST
On Tue, Nov 29, 2005 at 08:27:35PM -0700, Sirisha Muppavarapu wrote: > Hi... > > When I run my upc code, it says, > > WARNING: Node 0 running more threads (4) than there are physical CPU's (2) > enabling "polite", low-performance synchronization algorithms > ----------------------------------------------------------------------- > > I compiled my code with T=4 i.e 4 threads. The system is a linux system with 2 > processors. Can anyone plz suggest how to force the threads to run on all the > processors of the machine and not just 1 processor. How do I make sure that > code is indeed running on/using multiprocessors? Sirisha, Both CPUs *are* being used, unless I'm missing something. Do you have evidence that only one is used? The message above simply says that you're running 4 UPC threads on 2 CPUs. In this case, to avoid poor spin-lock performance, we revert to using pthread mutexes, which are more expensive in a contention-free situation, but much more well-behaved when contention is present. -- Jason Duell Future Technologies Group <jcduell_at_lbl_dot_gov> Computational Research Division Tel: +1-510-495-2354 Lawrence Berkeley National Laboratory