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/publicdomain/zero/1.0/
 */

import java.util.concurrent.*;

/** Barrier version of Jacobi iteration */
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 ThreadPhaserJacobi <matrix size> <max steps>");
            return;
        }

        ForkJoinPool fjp = new ForkJoinPool();
        //        int granularity = (n * n / fjp.getParallelism()) / 2;
        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:	1.10
Committed:	Sat Feb 16 21:37:44 2013 UTC (11 years, 2 months ago) by jsr166
Branch:	MAIN
Changes since 1.9:	+6 -1 lines
Log Message:	add missing public domain notices
#	User	Rev	Content
1	jsr166	1.10	/*
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/publicdomain/zero/1.0/
5			*/
6	dl	1.1
7			import java.util.concurrent.*;
8
9	jsr166	1.10	/** Barrier version of Jacobi iteration */
10	dl	1.1	public class FJPhaserJacobi {
11
12			static int dimGran;
13
14			static final double EPSILON = 0.0001; // convergence criterion
15
16			public static void main(String[] args) {
17			int n = 2048;
18			int steps = 1000;
19			try {
20			if (args.length > 0)
21			n = Integer.parseInt(args[0]);
22			if (args.length > 1)
23			steps = Integer.parseInt(args[1]);
24			}
25	jsr166	1.8
26	dl	1.1	catch (Exception e) {
27	dl	1.7	System.out.println("Usage: java ThreadPhaserJacobi <matrix size> <max steps>");
28	dl	1.1	return;
29			}
30	jsr166	1.8
31	dl	1.1	ForkJoinPool fjp = new ForkJoinPool();
32	dl	1.7	// int granularity = (n * n / fjp.getParallelism()) / 2;
33	dl	1.1	int granularity = n * n / fjp.getParallelism();
34	dl	1.7	dimGran = (int)(Math.sqrt(granularity));
35	jsr166	1.8
36	dl	1.1	// allocate enough space for edges
37			int dim = n+2;
38			int ncells = dim * dim;
39			double[][] a = new double[dim][dim];
40			double[][] b = new double[dim][dim];
41			// Initialize interiors to small value
42	jsr166	1.8	double smallVal = 1.0/dim;
43	dl	1.1	for (int i = 1; i < dim-1; ++i) {
44			for (int j = 1; j < dim-1; ++j)
45			a[i][j] = smallVal;
46			}
47			int nreps = 3;
48			for (int rep = 0; rep < nreps; ++rep) {
49			// Fill all edges with 1's.
50			for (int k = 0; k < dim; ++k) {
51			a[k][0] += 1.0;
52			a[k][n+1] += 1.0;
53			a[0][k] += 1.0;
54			a[n+1][k] += 1.0;
55			}
56			Driver driver = new Driver(a, b, 1, n, 1, n, steps);
57			long startTime = System.currentTimeMillis();
58			fjp.invoke(driver);
59	jsr166	1.8
60	dl	1.1	long time = System.currentTimeMillis() - startTime;
61	dl	1.7	double secs = ((double)time) / 1000.0;
62	jsr166	1.8
63	dl	1.1	System.out.println("Compute Time: " + secs);
64			System.out.println(fjp);
65
66			}
67	jsr166	1.8
68	dl	1.1	}
69
70			static class Segment extends CyclicAction {
71			double[][] A; // matrix to get old values from
72			double[][] B; // matrix to put new values into
73			// indices of current submatrix
74	jsr166	1.8	final int loRow;
75	dl	1.1	final int hiRow;
76			final int loCol;
77			final int hiCol;
78			volatile double maxDiff; // maximum difference between old and new values
79
80	jsr166	1.8	Segment(double[][] A, double[][] B,
81	dl	1.1	int loRow, int hiRow,
82	jsr166	1.8	int loCol, int hiCol,
83	dl	1.1	Phaser br) {
84			super(br);
85			this.A = A; this.B = B;
86			this.loRow = loRow; this.hiRow = hiRow;
87			this.loCol = loCol; this.hiCol = hiCol;
88			}
89
90			public void step() {
91			maxDiff = update(A, B);
92			double[][] tmp = A; A = B; B = tmp;
93			}
94
95			double update(double[][] a, double[][] b) {
96			double md = 0.0; // local for computing max diff
97
98			for (int i = loRow; i <= hiRow; ++i) {
99			for (int j = loCol; j <= hiCol; ++j) {
100			double v = 0.25 * (a[i-1][j] + a[i][j-1] +
101			a[i+1][j] + a[i][j+1]);
102			b[i][j] = v;
103
104			double diff = v - a[i][j];
105			if (diff < 0) diff = -diff;
106			if (diff > md) md = diff;
107			}
108			}
109
110			return md;
111			}
112	jsr166	1.8
113	dl	1.1	}
114
115			static class MyPhaser extends Phaser {
116			final int max;
117			MyPhaser(int steps) { this.max = steps - 1; }
118			public boolean onAdvance(int phase, int registeredParties) {
119			return phase >= max \|\| registeredParties <= 0;
120			}
121			}
122
123	jsr166	1.8	static class Driver extends RecursiveAction {
124	dl	1.1	double[][] A; // matrix to get old values from
125			double[][] B; // matrix to put new values into
126			final int loRow; // indices of current submatrix
127			final int hiRow;
128			final int loCol;
129			final int hiCol;
130			final int steps;
131	jsr166	1.8	Driver(double[][] mat1, double[][] mat2,
132	dl	1.1	int firstRow, int lastRow,
133			int firstCol, int lastCol,
134			int steps) {
135	jsr166	1.8
136	dl	1.1	this.A = mat1; this.B = mat2;
137			this.loRow = firstRow; this.hiRow = lastRow;
138			this.loCol = firstCol; this.hiCol = lastCol;
139			this.steps = steps;
140			}
141
142			public void compute() {
143			int rows = hiRow - loRow + 1;
144			int cols = hiCol - loCol + 1;
145	dl	1.7	int rblocks = (int)(Math.round((float)rows / dimGran));
146			int cblocks = (int)(Math.round((float)cols / dimGran));
147	jsr166	1.8
148	dl	1.1	int n = rblocks * cblocks;
149	jsr166	1.8
150	dl	1.1	System.out.println("Using " + n + " segments");
151	jsr166	1.8
152	dl	1.1	Segment[] segs = new Segment[n];
153			Phaser barrier = new MyPhaser(steps);
154			int k = 0;
155			for (int i = 0; i < rblocks; ++i) {
156			int lr = loRow + i * dimGran;
157			int hr = lr + dimGran;
158			if (i == rblocks-1) hr = hiRow;
159	jsr166	1.8
160	dl	1.1	for (int j = 0; j < cblocks; ++j) {
161			int lc = loCol + j * dimGran;
162			int hc = lc + dimGran;
163			if (j == cblocks-1) hc = hiCol;
164	jsr166	1.8
165	dl	1.1	segs[k] = new Segment(A, B, lr, hr, lc, hc, barrier);
166			++k;
167			}
168			}
169			invokeAll(segs);
170			double maxd = 0;
171			for (k = 0; k < n; ++k) {
172			double md = segs[k].maxDiff;
173			if (md > maxd) maxd = md;
174			}
175			System.out.println("Max diff after " + steps + " steps = " + maxd);
176			}
177			}
178			}