test/loops/FJPhaserJacobi.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */

// Barrier version of Jacobi iteration

import java.util.concurrent.*;
//import jsr166y.*;

public class FJPhaserJacobi {

    static int dimGran;

    static final double EPSILON = 0.0001;  // convergence criterion

    public static void main(String[] args) {
        int n = 2048;
        int steps = 1000;
        try {
            if (args.length > 0)
                n = Integer.parseInt(args[0]);
            if (args.length > 1)
                steps = Integer.parseInt(args[1]);
        }

        catch (Exception e) {
            System.out.println("Usage: java FJPhaserJacobi <matrix size> <max steps>");
            return;
        }

        ForkJoinPool fjp = new ForkJoinPool();
        int granularity = n * n / fjp.getParallelism();
        dimGran = (int)(Math.sqrt(granularity));

        // allocate enough space for edges
        int dim = n+2;
        int ncells = dim * dim;
        double[][] a = new double[dim][dim];
        double[][] b = new double[dim][dim];
        // Initialize interiors to small value
        double smallVal = 1.0/dim;
        for (int i = 1; i < dim-1; ++i) {
            for (int j = 1; j < dim-1; ++j)
                a[i][j] = smallVal;
        }
        int nreps = 3;
        for (int rep = 0; rep < nreps; ++rep) {
            // Fill all edges with 1's.
            for (int k = 0; k < dim; ++k) {
                a[k][0] += 1.0;
                a[k][n+1] += 1.0;
                a[0][k] += 1.0;
                a[n+1][k] += 1.0;
            }
            Driver driver = new Driver(a, b, 1, n, 1, n, steps);
            long startTime = System.currentTimeMillis();
            fjp.invoke(driver);

            long time = System.currentTimeMillis() - startTime;
            double secs = ((double)time) / 1000.0;

            System.out.println("Compute Time: " + secs);
            System.out.println(fjp);

        }

    }

    static class Segment extends CyclicAction {
        double[][] A; // matrix to get old values from
        double[][] B; // matrix to put new values into
        // indices of current submatrix
        final int loRow;
        final int hiRow;
        final int loCol;
        final int hiCol;
        volatile double maxDiff; // maximum difference between old and new values

        Segment(double[][] A, double[][] B,
                int loRow, int hiRow,
                int loCol, int hiCol,
                Phaser br) {
            super(br);
            this.A = A;   this.B = B;
            this.loRow = loRow; this.hiRow = hiRow;
            this.loCol = loCol; this.hiCol = hiCol;
        }

        public void step() {
            maxDiff = update(A, B);
            double[][] tmp = A; A = B; B = tmp;
        }

        double update(double[][] a, double[][] b) {
            double md = 0.0; // local for computing max diff

            for (int i = loRow; i <= hiRow; ++i) {
                for (int j = loCol; j <= hiCol; ++j) {
                    double v = 0.25 * (a[i-1][j] + a[i][j-1] +
                                       a[i+1][j] + a[i][j+1]);
                    b[i][j] = v;

                    double diff = v - a[i][j];
                    if (diff < 0) diff = -diff;
                    if (diff > md) md = diff;
                }
            }

            return md;
        }

    }

    static class MyPhaser extends Phaser {
        final int max;
        MyPhaser(int steps) { this.max = steps - 1; }
        public boolean onAdvance(int phase, int registeredParties) {
            return phase >= max || registeredParties <= 0;
        }
    }

    static class Driver extends RecursiveAction {
        double[][] A; // matrix to get old values from
        double[][] B; // matrix to put new values into
        final int loRow;   // indices of current submatrix
        final int hiRow;
        final int loCol;
        final int hiCol;
        final int steps;
        Driver(double[][] mat1, double[][] mat2,
               int firstRow, int lastRow,
               int firstCol, int lastCol,
               int steps) {

            this.A = mat1;   this.B = mat2;
            this.loRow = firstRow; this.hiRow = lastRow;
            this.loCol = firstCol; this.hiCol = lastCol;
            this.steps = steps;
        }

        public void compute() {
            int rows = hiRow - loRow + 1;
            int cols = hiCol - loCol + 1;
            int rblocks = (int)(Math.round((float)rows / dimGran));
            int cblocks = (int)(Math.round((float)cols / dimGran));

            int n = rblocks * cblocks;

            System.out.println("Using " + n + " segments");

            Segment[] segs = new Segment[n];
            Phaser barrier = new MyPhaser(steps);
            int k = 0;
            for (int i = 0; i < rblocks; ++i) {
                int lr = loRow + i * dimGran;
                int hr = lr + dimGran;
                if (i == rblocks-1) hr = hiRow;

                for (int j = 0; j < cblocks; ++j) {
                    int lc = loCol + j * dimGran;
                    int hc = lc + dimGran;
                    if (j == cblocks-1) hc = hiCol;

                    segs[k] = new Segment(A, B, lr, hr, lc, hc, barrier);
                    ++k;
                }
            }
            invokeAll(segs);
            double maxd = 0;
            for (k = 0; k < n; ++k) {
                double md = segs[k].maxDiff;
                if (md > maxd) maxd = md;
            }
            System.out.println("Max diff after " + steps + " steps = " + maxd);
        }
    }
}
Revision:	1.4
Committed:	Fri Oct 30 14:15:04 2009 UTC (14 years, 6 months ago) by dl
Branch:	MAIN
Changes since 1.3:	+6 -0 lines
Log Message:	Missing file headers
#	User	Rev	Content
1	dl	1.4	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/licenses/publicdomain
5			*/
6
7	dl	1.1	// Barrier version of Jacobi iteration
8
9			import java.util.concurrent.*;
10			//import jsr166y.*;
11
12			public class FJPhaserJacobi {
13
14			static int dimGran;
15
16			static final double EPSILON = 0.0001; // convergence criterion
17
18			public static void main(String[] args) {
19			int n = 2048;
20			int steps = 1000;
21			try {
22			if (args.length > 0)
23			n = Integer.parseInt(args[0]);
24			if (args.length > 1)
25			steps = Integer.parseInt(args[1]);
26			}
27	jsr166	1.2
28	dl	1.1	catch (Exception e) {
29	jsr166	1.3	System.out.println("Usage: java FJPhaserJacobi <matrix size> <max steps>");
30	dl	1.1	return;
31			}
32	jsr166	1.2
33	dl	1.1	ForkJoinPool fjp = new ForkJoinPool();
34			int granularity = n * n / fjp.getParallelism();
35			dimGran = (int)(Math.sqrt(granularity));
36	jsr166	1.2
37	dl	1.1	// allocate enough space for edges
38			int dim = n+2;
39			int ncells = dim * dim;
40			double[][] a = new double[dim][dim];
41			double[][] b = new double[dim][dim];
42			// Initialize interiors to small value
43	jsr166	1.2	double smallVal = 1.0/dim;
44	dl	1.1	for (int i = 1; i < dim-1; ++i) {
45			for (int j = 1; j < dim-1; ++j)
46			a[i][j] = smallVal;
47			}
48			int nreps = 3;
49			for (int rep = 0; rep < nreps; ++rep) {
50			// Fill all edges with 1's.
51			for (int k = 0; k < dim; ++k) {
52			a[k][0] += 1.0;
53			a[k][n+1] += 1.0;
54			a[0][k] += 1.0;
55			a[n+1][k] += 1.0;
56			}
57			Driver driver = new Driver(a, b, 1, n, 1, n, steps);
58			long startTime = System.currentTimeMillis();
59			fjp.invoke(driver);
60	jsr166	1.2
61	dl	1.1	long time = System.currentTimeMillis() - startTime;
62			double secs = ((double)time) / 1000.0;
63	jsr166	1.2
64	dl	1.1	System.out.println("Compute Time: " + secs);
65			System.out.println(fjp);
66
67			}
68	jsr166	1.2
69	dl	1.1	}
70
71			static class Segment extends CyclicAction {
72			double[][] A; // matrix to get old values from
73			double[][] B; // matrix to put new values into
74			// indices of current submatrix
75	jsr166	1.2	final int loRow;
76	dl	1.1	final int hiRow;
77			final int loCol;
78			final int hiCol;
79			volatile double maxDiff; // maximum difference between old and new values
80
81	jsr166	1.2	Segment(double[][] A, double[][] B,
82	dl	1.1	int loRow, int hiRow,
83	jsr166	1.2	int loCol, int hiCol,
84	dl	1.1	Phaser br) {
85			super(br);
86			this.A = A; this.B = B;
87			this.loRow = loRow; this.hiRow = hiRow;
88			this.loCol = loCol; this.hiCol = hiCol;
89			}
90
91			public void step() {
92			maxDiff = update(A, B);
93			double[][] tmp = A; A = B; B = tmp;
94			}
95
96			double update(double[][] a, double[][] b) {
97			double md = 0.0; // local for computing max diff
98
99			for (int i = loRow; i <= hiRow; ++i) {
100			for (int j = loCol; j <= hiCol; ++j) {
101			double v = 0.25 * (a[i-1][j] + a[i][j-1] +
102			a[i+1][j] + a[i][j+1]);
103			b[i][j] = v;
104
105			double diff = v - a[i][j];
106			if (diff < 0) diff = -diff;
107			if (diff > md) md = diff;
108			}
109			}
110
111			return md;
112			}
113	jsr166	1.2
114	dl	1.1	}
115
116			static class MyPhaser extends Phaser {
117			final int max;
118			MyPhaser(int steps) { this.max = steps - 1; }
119			public boolean onAdvance(int phase, int registeredParties) {
120			return phase >= max \|\| registeredParties <= 0;
121			}
122			}
123
124	jsr166	1.2	static class Driver extends RecursiveAction {
125	dl	1.1	double[][] A; // matrix to get old values from
126			double[][] B; // matrix to put new values into
127			final int loRow; // indices of current submatrix
128			final int hiRow;
129			final int loCol;
130			final int hiCol;
131			final int steps;
132	jsr166	1.2	Driver(double[][] mat1, double[][] mat2,
133	dl	1.1	int firstRow, int lastRow,
134			int firstCol, int lastCol,
135			int steps) {
136	jsr166	1.2
137	dl	1.1	this.A = mat1; this.B = mat2;
138			this.loRow = firstRow; this.hiRow = lastRow;
139			this.loCol = firstCol; this.hiCol = lastCol;
140			this.steps = steps;
141			}
142
143			public void compute() {
144			int rows = hiRow - loRow + 1;
145			int cols = hiCol - loCol + 1;
146			int rblocks = (int)(Math.round((float)rows / dimGran));
147			int cblocks = (int)(Math.round((float)cols / dimGran));
148	jsr166	1.2
149	dl	1.1	int n = rblocks * cblocks;
150	jsr166	1.2
151	dl	1.1	System.out.println("Using " + n + " segments");
152	jsr166	1.2
153	dl	1.1	Segment[] segs = new Segment[n];
154			Phaser barrier = new MyPhaser(steps);
155			int k = 0;
156			for (int i = 0; i < rblocks; ++i) {
157			int lr = loRow + i * dimGran;
158			int hr = lr + dimGran;
159			if (i == rblocks-1) hr = hiRow;
160	jsr166	1.2
161	dl	1.1	for (int j = 0; j < cblocks; ++j) {
162			int lc = loCol + j * dimGran;
163			int hc = lc + dimGran;
164			if (j == cblocks-1) hc = hiCol;
165	jsr166	1.2
166	dl	1.1	segs[k] = new Segment(A, B, lr, hr, lc, hc, barrier);
167			++k;
168			}
169			}
170			invokeAll(segs);
171			double maxd = 0;
172			for (k = 0; k < n; ++k) {
173			double md = segs[k].maxDiff;
174			if (md > maxd) maxd = md;
175			}
176			System.out.println("Max diff after " + steps + " steps = " + maxd);
177			}
178			}
179			}