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 |
|
8 |
import jsr166y.*; |
9 |
import extra166y.*; |
10 |
import static extra166y.Ops.*; |
11 |
import java.util.*; |
12 |
import java.util.concurrent.*; |
13 |
|
14 |
public class DoubleCumulateDemo { |
15 |
static final int NCPU = Runtime.getRuntime().availableProcessors(); |
16 |
/** for time conversion */ |
17 |
static final long NPS = (1000L * 1000 * 1000); |
18 |
|
19 |
static boolean check = false; // true; |
20 |
|
21 |
public static void main(String[] args) throws Exception { |
22 |
check = args.length > 0; |
23 |
int n = 1 << 19; |
24 |
int reps = 1 << 9; |
25 |
int tests = 4; |
26 |
double[] array = new double[n]; |
27 |
long last, now; |
28 |
double elapsed; |
29 |
|
30 |
for (int j = 0; j < tests; ++j) { |
31 |
fill(array); |
32 |
last = System.nanoTime(); |
33 |
for (int k = 0; k < reps; ++k) { |
34 |
seqCumulate(array); |
35 |
if (k == 0 && check) |
36 |
check(array); |
37 |
} |
38 |
now = System.nanoTime(); |
39 |
elapsed = (double)(now - last) / (NPS); |
40 |
System.out.printf("seq : %9.5f\n", elapsed); |
41 |
} |
42 |
|
43 |
for (int sweeps = 0; sweeps < 2; ++sweeps) { |
44 |
for (int i = 2; i <= NCPU; i <<= 1) { |
45 |
ForkJoinPool fjp = new ForkJoinPool(i); |
46 |
oneRun(fjp, array, i, reps, tests); |
47 |
fjp.shutdown(); |
48 |
} |
49 |
for (int i = NCPU; i >= 1; i >>>= 1) { |
50 |
ForkJoinPool fjp = new ForkJoinPool(i); |
51 |
oneRun(fjp, array, i, reps, tests); |
52 |
fjp.shutdown(); |
53 |
} |
54 |
} |
55 |
} |
56 |
|
57 |
static void oneRun(ForkJoinPool fjp, |
58 |
double[] array, int nthreads, |
59 |
int reps, int tests) throws Exception { |
60 |
ParallelDoubleArray pa = ParallelDoubleArray.createUsingHandoff(array, fjp); |
61 |
long last, now; |
62 |
long steals = fjp.getStealCount(); |
63 |
// long syncs = fjp.getSyncCount(); |
64 |
for (int j = 0; j < tests; ++j) { |
65 |
fill(array); |
66 |
last = System.nanoTime(); |
67 |
for (int k = 0; k < reps; ++k) { |
68 |
pa.cumulateSum(); |
69 |
if (k == 0 && check) |
70 |
check(array); |
71 |
} |
72 |
now = System.nanoTime(); |
73 |
double elapsed = (double)(now - last) / (NPS); |
74 |
last = now; |
75 |
long sc = fjp.getStealCount(); |
76 |
long scount = (sc - steals) / reps; |
77 |
steals = sc; |
78 |
// long tc = fjp.getSyncCount(); |
79 |
// long tcount = (tc - syncs) / reps; |
80 |
// syncs = tc; |
81 |
|
82 |
// System.out.printf("ps %2d: %9.5f Steals:%6d Syncs %6d\n", nthreads, elapsed, scount, tcount); |
83 |
System.out.printf("ps %2d: %9.5f Steals:%6d\n", nthreads, elapsed, scount); |
84 |
} |
85 |
Thread.sleep(100); |
86 |
} |
87 |
|
88 |
static void check(double[] array) { |
89 |
for (int i = 0; i < array.length; ++i) { |
90 |
double sum = i + 1; |
91 |
if (array[i] != sum) { |
92 |
System.out.println("i: " + i + " sum: " + sum + " element:" + array[i]); |
93 |
throw new Error(); |
94 |
} |
95 |
} |
96 |
// System.out.print("*"); |
97 |
} |
98 |
|
99 |
static void fill(double[] array) { |
100 |
for (int i = 0; i < array.length; ++i) |
101 |
array[i] = 1; |
102 |
} |
103 |
|
104 |
static double seqCumulate(double[] array) { |
105 |
double sum = 0; |
106 |
for (int i = 0; i < array.length; ++i) |
107 |
sum = array[i] += sum; |
108 |
return sum; |
109 |
} |
110 |
} |