test/loops/FJJacobi.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
 */

// Jacobi iteration on a mesh. Based loosely on a Filaments demo

import java.util.concurrent.*;

public class FJJacobi {

    static final int DEFAULT_GRANULARITY = 4096; // 1024;

    /**
     * The maximum number of matrix cells
     * at which to stop recursing down and instead directly update.
     */
    static final double EPSILON = 0.0001;  // convergence criterion

    public static void main(String[] args) throws Exception {
        int n = 2048;
        int steps = 1000;
        int granularity = DEFAULT_GRANULARITY;

        try {
            if (args.length > 0)
                n = Integer.parseInt(args[0]);
            if (args.length > 1)
                steps = Integer.parseInt(args[1]);
            if (args.length > 2)
                granularity = Integer.parseInt(args[2]);
        }

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

        ForkJoinPool fjp = new ForkJoinPool();

        // 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 = EPSILON; // 1.0/dim;
        for (int i = 1; i < dim-1; ++i) {
            for (int j = 1; j < dim-1; ++j)
                a[i][j] = smallVal;
        }
        // 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;
            b[k][0] = 1.0;
            b[k][n+1] = 1.0;
            b[0][k] = 1.0;
            b[n+1][k] = 1.0;
        }
        int nreps = 10;
        for (int rep = 0; rep < nreps; ++rep) {
            Driver driver = new Driver(a, b, 1, n, 1, n, steps, granularity);

            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);
        }
    }


    abstract static class MatrixTree extends RecursiveAction {
        // maximum difference between old and new values
        double maxDiff;
        public final double directCompute() {
            compute();
            return maxDiff;
        }
        public final double joinAndReinitialize(double md) {
            if (tryUnfork())
                compute();
            else {
                quietlyJoin();
                reinitialize();
            }
            double m = maxDiff;
            return (md > m)? md : m;
        }

    }


    static final class LeafNode extends MatrixTree {
        final double[][] A; // matrix to get old values from
        final double[][] B; // matrix to put new values into

        // indices of current submatrix
        final int loRow;    final int hiRow;
        final int loCol;    final int hiCol;

        int steps = 0; // track even/odd steps

        LeafNode(double[][] A, double[][] B,
                 int loRow, int hiRow,
                 int loCol, int hiCol) {
            this.A = A;   this.B = B;
            this.loRow = loRow; this.hiRow = hiRow;
            this.loCol = loCol; this.hiCol = hiCol;
        }

        public void compute() {
            boolean AtoB = (steps++ & 1) == 0;
            double[][] a = (AtoB)? A : B;
            double[][] b = (AtoB)? B : A;

            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;
                }
            }

            maxDiff = md;
        }
    }

    static final class FourNode extends MatrixTree {
        final MatrixTree q1;
        final MatrixTree q2;
        final MatrixTree q3;
        final MatrixTree q4;
        FourNode(MatrixTree q1, MatrixTree q2,
                 MatrixTree q3, MatrixTree q4) {
            this.q1 = q1; this.q2 = q2; this.q3 = q3; this.q4 = q4;
        }

        public void compute() {
            q4.fork();
            q3.fork();
            q2.fork();
            double md = q1.directCompute();
            md = q2.joinAndReinitialize(md);
            md = q3.joinAndReinitialize(md);
            md = q4.joinAndReinitialize(md);
            maxDiff = md;
        }
    }


    static final class TwoNode extends MatrixTree {
        final MatrixTree q1;
        final MatrixTree q2;

        TwoNode(MatrixTree q1, MatrixTree q2) {
            this.q1 = q1; this.q2 = q2;
        }

        public void compute() {
            q2.fork();
            maxDiff = q2.joinAndReinitialize(q1.directCompute());
        }

    }


    static final class Driver extends RecursiveAction {
        MatrixTree mat;
        double[][] A; double[][] B;
        int firstRow; int lastRow;
        int firstCol; int lastCol;
        final int steps;
        final int leafs;
        int nleaf;

        Driver(double[][] A, double[][] B,
               int firstRow, int lastRow,
               int firstCol, int lastCol,
               int steps, int leafs) {
            this.A = A;
            this.B = B;
            this.firstRow = firstRow;
            this.firstCol = firstCol;
            this.lastRow = lastRow;
            this.lastCol = lastCol;
            this.steps = steps;
            this.leafs = leafs;
            mat = build(A, B, firstRow, lastRow, firstCol, lastCol, leafs);
            System.out.println("Using " + nleaf + " segments");

        }

        MatrixTree build(double[][] a, double[][] b,
                         int lr, int hr, int lc, int hc, int leafs) {
            int rows = (hr - lr + 1);
            int cols = (hc - lc + 1);

            int mr = (lr + hr) >>> 1; // midpoints
            int mc = (lc + hc) >>> 1;

            int hrows = (mr - lr + 1);
            int hcols = (mc - lc + 1);

            if (rows * cols <= leafs) {
                ++nleaf;
                return new LeafNode(a, b, lr, hr, lc, hc);
            }
            else if (hrows * hcols >= leafs) {
                return new FourNode(build(a, b, lr,   mr, lc,   mc, leafs),
                                    build(a, b, lr,   mr, mc+1, hc, leafs),
                                    build(a, b, mr+1, hr, lc,   mc, leafs),
                                    build(a, b, mr+1, hr, mc+1, hc, leafs));
            }
            else if (cols >= rows) {
                return new TwoNode(build(a, b, lr, hr, lc,   mc, leafs),
                                   build(a, b, lr, hr, mc+1, hc, leafs));
            }
            else {
                return new TwoNode(build(a, b, lr,   mr, lc, hc, leafs),
                                   build(a, b, mr+1, hr, lc, hc, leafs));

            }
        }

        static void doCompute(MatrixTree m, int s) {
            for (int i = 0; i < s; ++i) {
                m.invoke();
                m.reinitialize();
            }
        }

        public void compute() {
            doCompute(mat, steps);
            double md = mat.maxDiff;
            System.out.println("max diff after " + steps + " steps = " + md);
        }
    }


}
Revision:	1.8
Committed:	Sat Oct 16 16:22:56 2010 UTC (13 years, 7 months ago) by jsr166
Branch:	MAIN
Changes since 1.7:	+1 -2 lines
Log Message:	coding style
#	Content
1	/*
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	// Jacobi iteration on a mesh. Based loosely on a Filaments demo
8
9	import java.util.concurrent.*;
10
11	public class FJJacobi {
12
13	static final int DEFAULT_GRANULARITY = 4096; // 1024;
14
15	/**
16	* The maximum number of matrix cells
17	* at which to stop recursing down and instead directly update.
18	*/
19	static final double EPSILON = 0.0001; // convergence criterion
20
21	public static void main(String[] args) throws Exception {
22	int n = 2048;
23	int steps = 1000;
24	int granularity = DEFAULT_GRANULARITY;
25
26	try {
27	if (args.length > 0)
28	n = Integer.parseInt(args[0]);
29	if (args.length > 1)
30	steps = Integer.parseInt(args[1]);
31	if (args.length > 2)
32	granularity = Integer.parseInt(args[2]);
33	}
34
35	catch (Exception e) {
36	System.out.println("Usage: java FJJacobi <matrix size> <max steps> [<leafcells>]");
37	return;
38	}
39
40	ForkJoinPool fjp = new ForkJoinPool();
41
42	// allocate enough space for edges
43	int dim = n+2;
44	int ncells = dim * dim;
45	double[][] a = new double[dim][dim];
46	double[][] b = new double[dim][dim];
47	// Initialize interiors to small value
48	double smallVal = EPSILON; // 1.0/dim;
49	for (int i = 1; i < dim-1; ++i) {
50	for (int j = 1; j < dim-1; ++j)
51	a[i][j] = smallVal;
52	}
53	// Fill all edges with 1's.
54	for (int k = 0; k < dim; ++k) {
55	a[k][0] = 1.0;
56	a[k][n+1] = 1.0;
57	a[0][k] = 1.0;
58	a[n+1][k] = 1.0;
59	b[k][0] = 1.0;
60	b[k][n+1] = 1.0;
61	b[0][k] = 1.0;
62	b[n+1][k] = 1.0;
63	}
64	int nreps = 10;
65	for (int rep = 0; rep < nreps; ++rep) {
66	Driver driver = new Driver(a, b, 1, n, 1, n, steps, granularity);
67
68	long startTime = System.currentTimeMillis();
69	fjp.invoke(driver);
70
71	long time = System.currentTimeMillis() - startTime;
72	double secs = ((double)time) / 1000.0;
73
74	System.out.println("Compute Time: " + secs);
75	System.out.println(fjp);
76	}
77	}
78
79
80	abstract static class MatrixTree extends RecursiveAction {
81	// maximum difference between old and new values
82	double maxDiff;
83	public final double directCompute() {
84	compute();
85	return maxDiff;
86	}
87	public final double joinAndReinitialize(double md) {
88	if (tryUnfork())
89	compute();
90	else {
91	quietlyJoin();
92	reinitialize();
93	}
94	double m = maxDiff;
95	return (md > m)? md : m;
96	}
97
98	}
99
100
101	static final class LeafNode extends MatrixTree {
102	final double[][] A; // matrix to get old values from
103	final double[][] B; // matrix to put new values into
104
105	// indices of current submatrix
106	final int loRow; final int hiRow;
107	final int loCol; final int hiCol;
108
109	int steps = 0; // track even/odd steps
110
111	LeafNode(double[][] A, double[][] B,
112	int loRow, int hiRow,
113	int loCol, int hiCol) {
114	this.A = A; this.B = B;
115	this.loRow = loRow; this.hiRow = hiRow;
116	this.loCol = loCol; this.hiCol = hiCol;
117	}
118
119	public void compute() {
120	boolean AtoB = (steps++ & 1) == 0;
121	double[][] a = (AtoB)? A : B;
122	double[][] b = (AtoB)? B : A;
123
124	double md = 0.0; // local for computing max diff
125
126	for (int i = loRow; i <= hiRow; ++i) {
127	for (int j = loCol; j <= hiCol; ++j) {
128	double v = 0.25 * (a[i-1][j] + a[i][j-1] +
129	a[i+1][j] + a[i][j+1]);
130	b[i][j] = v;
131
132	double diff = v - a[i][j];
133	if (diff < 0) diff = -diff;
134	if (diff > md) md = diff;
135	}
136	}
137
138	maxDiff = md;
139	}
140	}
141
142	static final class FourNode extends MatrixTree {
143	final MatrixTree q1;
144	final MatrixTree q2;
145	final MatrixTree q3;
146	final MatrixTree q4;
147	FourNode(MatrixTree q1, MatrixTree q2,
148	MatrixTree q3, MatrixTree q4) {
149	this.q1 = q1; this.q2 = q2; this.q3 = q3; this.q4 = q4;
150	}
151
152	public void compute() {
153	q4.fork();
154	q3.fork();
155	q2.fork();
156	double md = q1.directCompute();
157	md = q2.joinAndReinitialize(md);
158	md = q3.joinAndReinitialize(md);
159	md = q4.joinAndReinitialize(md);
160	maxDiff = md;
161	}
162	}
163
164
165	static final class TwoNode extends MatrixTree {
166	final MatrixTree q1;
167	final MatrixTree q2;
168
169	TwoNode(MatrixTree q1, MatrixTree q2) {
170	this.q1 = q1; this.q2 = q2;
171	}
172
173	public void compute() {
174	q2.fork();
175	maxDiff = q2.joinAndReinitialize(q1.directCompute());
176	}
177
178	}
179
180
181	static final class Driver extends RecursiveAction {
182	MatrixTree mat;
183	double[][] A; double[][] B;
184	int firstRow; int lastRow;
185	int firstCol; int lastCol;
186	final int steps;
187	final int leafs;
188	int nleaf;
189
190	Driver(double[][] A, double[][] B,
191	int firstRow, int lastRow,
192	int firstCol, int lastCol,
193	int steps, int leafs) {
194	this.A = A;
195	this.B = B;
196	this.firstRow = firstRow;
197	this.firstCol = firstCol;
198	this.lastRow = lastRow;
199	this.lastCol = lastCol;
200	this.steps = steps;
201	this.leafs = leafs;
202	mat = build(A, B, firstRow, lastRow, firstCol, lastCol, leafs);
203	System.out.println("Using " + nleaf + " segments");
204
205	}
206
207	MatrixTree build(double[][] a, double[][] b,
208	int lr, int hr, int lc, int hc, int leafs) {
209	int rows = (hr - lr + 1);
210	int cols = (hc - lc + 1);
211
212	int mr = (lr + hr) >>> 1; // midpoints
213	int mc = (lc + hc) >>> 1;
214
215	int hrows = (mr - lr + 1);
216	int hcols = (mc - lc + 1);
217
218	if (rows * cols <= leafs) {
219	++nleaf;
220	return new LeafNode(a, b, lr, hr, lc, hc);
221	}
222	else if (hrows * hcols >= leafs) {
223	return new FourNode(build(a, b, lr, mr, lc, mc, leafs),
224	build(a, b, lr, mr, mc+1, hc, leafs),
225	build(a, b, mr+1, hr, lc, mc, leafs),
226	build(a, b, mr+1, hr, mc+1, hc, leafs));
227	}
228	else if (cols >= rows) {
229	return new TwoNode(build(a, b, lr, hr, lc, mc, leafs),
230	build(a, b, lr, hr, mc+1, hc, leafs));
231	}
232	else {
233	return new TwoNode(build(a, b, lr, mr, lc, hc, leafs),
234	build(a, b, mr+1, hr, lc, hc, leafs));
235
236	}
237	}
238
239	static void doCompute(MatrixTree m, int s) {
240	for (int i = 0; i < s; ++i) {
241	m.invoke();
242	m.reinitialize();
243	}
244	}
245
246	public void compute() {
247	doCompute(mat, steps);
248	double md = mat.maxDiff;
249	System.out.println("max diff after " + steps + " steps = " + md);
250	}
251	}
252
253
254	}