| 1 |
< |
// Barrier version of Jacobi iteration |
| 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/publicdomain/zero/1.0/ |
| 5 |
> |
*/ |
| 6 |
|
|
| 7 |
|
import java.util.concurrent.*; |
| 4 |
– |
//import jsr166y.*; |
| 8 |
|
|
| 9 |
+ |
/** Barrier version of Jacobi iteration */ |
| 10 |
|
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) { |
| 16 |
> |
public static void main(String[] args) throws Exception { |
| 17 |
|
int n = 2048; |
| 18 |
|
int steps = 1000; |
| 19 |
|
try { |
| 22 |
|
if (args.length > 1) |
| 23 |
|
steps = Integer.parseInt(args[1]); |
| 24 |
|
} |
| 25 |
< |
|
| 25 |
> |
|
| 26 |
|
catch (Exception e) { |
| 27 |
|
System.out.println("Usage: java ThreadPhaserJacobi <matrix size> <max steps>"); |
| 28 |
|
return; |
| 29 |
|
} |
| 30 |
< |
|
| 31 |
< |
ForkJoinPool fjp = new ForkJoinPool(); |
| 30 |
> |
|
| 31 |
> |
// ForkJoinPool fjp = new ForkJoinPool(); |
| 32 |
> |
ForkJoinPool fjp = ForkJoinPool.commonPool(); |
| 33 |
> |
|
| 34 |
> |
// int granularity = (n * n / fjp.getParallelism()) / 2; |
| 35 |
|
int granularity = n * n / fjp.getParallelism(); |
| 36 |
|
dimGran = (int)(Math.sqrt(granularity)); |
| 37 |
< |
|
| 37 |
> |
|
| 38 |
|
// allocate enough space for edges |
| 39 |
|
int dim = n+2; |
| 40 |
|
int ncells = dim * dim; |
| 41 |
|
double[][] a = new double[dim][dim]; |
| 42 |
|
double[][] b = new double[dim][dim]; |
| 43 |
|
// Initialize interiors to small value |
| 44 |
< |
double smallVal = 1.0/dim; |
| 44 |
> |
double smallVal = 1.0/dim; |
| 45 |
|
for (int i = 1; i < dim-1; ++i) { |
| 46 |
|
for (int j = 1; j < dim-1; ++j) |
| 47 |
|
a[i][j] = smallVal; |
| 48 |
|
} |
| 49 |
< |
int nreps = 3; |
| 49 |
> |
int nreps = 10; |
| 50 |
|
for (int rep = 0; rep < nreps; ++rep) { |
| 51 |
|
// Fill all edges with 1's. |
| 52 |
|
for (int k = 0; k < dim; ++k) { |
| 58 |
|
Driver driver = new Driver(a, b, 1, n, 1, n, steps); |
| 59 |
|
long startTime = System.currentTimeMillis(); |
| 60 |
|
fjp.invoke(driver); |
| 61 |
< |
|
| 61 |
> |
|
| 62 |
|
long time = System.currentTimeMillis() - startTime; |
| 63 |
|
double secs = ((double)time) / 1000.0; |
| 64 |
< |
|
| 64 |
> |
|
| 65 |
|
System.out.println("Compute Time: " + secs); |
| 66 |
|
System.out.println(fjp); |
| 67 |
< |
|
| 67 |
> |
Thread.sleep(1000); |
| 68 |
|
} |
| 62 |
– |
|
| 69 |
|
} |
| 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 |
< |
final int loRow; |
| 75 |
> |
final int loRow; |
| 76 |
|
final int hiRow; |
| 77 |
|
final int loCol; |
| 78 |
|
final int hiCol; |
| 79 |
|
volatile double maxDiff; // maximum difference between old and new values |
| 80 |
|
|
| 81 |
< |
Segment(double[][] A, double[][] B, |
| 81 |
> |
Segment(double[][] A, double[][] B, |
| 82 |
|
int loRow, int hiRow, |
| 83 |
< |
int loCol, int hiCol, |
| 83 |
> |
int loCol, int hiCol, |
| 84 |
|
Phaser br) { |
| 85 |
|
super(br); |
| 86 |
|
this.A = A; this.B = B; |
| 110 |
|
|
| 111 |
|
return md; |
| 112 |
|
} |
| 113 |
< |
|
| 113 |
> |
|
| 114 |
|
} |
| 115 |
|
|
| 116 |
|
static class MyPhaser extends Phaser { |
| 121 |
|
} |
| 122 |
|
} |
| 123 |
|
|
| 124 |
< |
static class Driver extends RecursiveAction { |
| 124 |
> |
static class Driver extends RecursiveAction { |
| 125 |
|
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 |
| 129 |
|
final int loCol; |
| 130 |
|
final int hiCol; |
| 131 |
|
final int steps; |
| 132 |
< |
Driver(double[][] mat1, double[][] mat2, |
| 132 |
> |
Driver(double[][] mat1, double[][] mat2, |
| 133 |
|
int firstRow, int lastRow, |
| 134 |
|
int firstCol, int lastCol, |
| 135 |
|
int steps) { |
| 136 |
< |
|
| 136 |
> |
|
| 137 |
|
this.A = mat1; this.B = mat2; |
| 138 |
|
this.loRow = firstRow; this.hiRow = lastRow; |
| 139 |
|
this.loCol = firstCol; this.hiCol = lastCol; |
| 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 |
< |
|
| 146 |
> |
int rblocks = Math.round((float)rows / dimGran); |
| 147 |
> |
int cblocks = Math.round((float)cols / dimGran); |
| 148 |
> |
|
| 149 |
|
int n = rblocks * cblocks; |
| 150 |
< |
|
| 150 |
> |
|
| 151 |
|
System.out.println("Using " + n + " segments"); |
| 152 |
< |
|
| 152 |
> |
|
| 153 |
|
Segment[] segs = new Segment[n]; |
| 154 |
|
Phaser barrier = new MyPhaser(steps); |
| 155 |
|
int k = 0; |
| 157 |
|
int lr = loRow + i * dimGran; |
| 158 |
|
int hr = lr + dimGran; |
| 159 |
|
if (i == rblocks-1) hr = hiRow; |
| 160 |
< |
|
| 160 |
> |
|
| 161 |
|
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 |
< |
|
| 165 |
> |
|
| 166 |
|
segs[k] = new Segment(A, B, lr, hr, lc, hc, barrier); |
| 167 |
|
++k; |
| 168 |
|
} |
| 177 |
|
} |
| 178 |
|
} |
| 179 |
|
} |
| 174 |
– |
|
