Jim LaGrone <jlagr...@cs.uh.edu> wrote on 08/31/2009 10:20:29 AM:
> I spoke too soon. It compiled but didn't run. Still have the
> BadPlaceExeption. This is the code:
>
> //declared as Class members
> var regionS: Region{rank==2};
> var distS: Dist{rank==2};
> var S: Array[Complex](distS);
>
> //code from member method
> regionS = [0..N-1, 0..Mc-1];
> distS = Dist.makeBlock(regionS,0);
>
> S = Array.make[Complex](distS,
> (val (i,j):Point) => new Complex ( real(i*Mc+j), image(i*Mc+j) )
);
Jim,
See my comments regarding fields vs. local variables, and static vs.
instance methods. If real() and image() are instance methods, they
will be invoked via "this", which lives in place 0. Also, if Mc is
an instance field, it will also live in place 0. The initializer
essentially runs in an ateach loop, so the same restrictions apply.
> I'm still confused about the number of places. It shows 4 places
> printing NativeRuntime.MAX_PLACES on my dual core machine. I'll attach
> output from execution.
>
> Jim
X10 will not automatically compute the optimal number of places --
you have to tell it how many places to use. For the Java backend
the default is 4 places, regardless of the number of actual cores.
For the C++ backend it's however many processes you spawn (runx10
will only spawn one).
Hope this helps,
Igor
> [attachment "exec.out" deleted by Igor Peshansky/Watson/IBM]
>
> On 28 Aug 2009, at 8:29 PM, Josh Milthorpe wrote:
>
> > If I correctly understand the intent, you're trying to initialize
> > each element of S : Array[Complex] based on some values in the real
> > and image rails. However I don't think that's what the above code
> > achieves.
> >
> > The outer loop iterates over all places included in distS. The
> > inner loop iterates over every point in the region of S. Because
> > distS is a block distribution over all places, this means that an
> > activity will be started at each place, and each activity will
> > attempt to assign to every element of S - including those elements
> > that reside at other places. I suspect that this is the cause of
> > the BPE.
> >
> > (As an aside, S is not distributed, because distS is not used in the
> > initializer. To make it distributed, use
> > distS = Dist.makeBlock(distS,0);
> > rather than
> > distS = Dist.makeBlock(regionS,0);
> > )
> > You could initialize S in a single statement using an Array
> > initializer function, something like:
> >
> > S = Array.make[Complex](distS, (val (i,j): Point) => new Complex
> > (real(i*Mc+j), image(i*Mc+j)));
>
> This is what I was looking for but couldn't make it work. I don't know
> what I had before, but this works. Thanks!
>
> >
> > BTW is the use of "image" rather than "imaginary" an American vs.
> > British thing? I haven't heard this term used before.
>
> I'm porting a benchmark someone else wrote in C. I'm just using the
> same identifiers. Personally, I would have used "imag".
>
> Jim
--
Igor Peshansky (note the spelling change!)
IBM T.J. Watson Research Center
XJ: No More Pain for XML's Gain (http://www.research.ibm.com/xj/)
X10: Parallel Productivity and Performance (http://x10.sf.net/)
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