1 |
dl |
1.1 |
//import jsr166y.*; |
2 |
|
|
import java.util.*; |
3 |
|
|
import java.util.concurrent.*; |
4 |
|
|
|
5 |
|
|
public final class DynamicLeftSpineFib extends RecursiveAction { |
6 |
|
|
|
7 |
|
|
// Performance-tuning constant: |
8 |
|
|
static long lastStealCount; |
9 |
|
|
|
10 |
|
|
public static void main(String[] args) throws Exception { |
11 |
|
|
int procs = 0; |
12 |
|
|
int num = 43; |
13 |
|
|
try { |
14 |
|
|
if (args.length > 0) |
15 |
|
|
procs = Integer.parseInt(args[0]); |
16 |
|
|
if (args.length > 1) |
17 |
|
|
num = Integer.parseInt(args[1]); |
18 |
|
|
} |
19 |
|
|
catch (Exception e) { |
20 |
|
|
System.out.println("Usage: java DynamicLeftSpineFib <threads> <number> [<sequntialThreshold>]"); |
21 |
|
|
return; |
22 |
|
|
} |
23 |
|
|
|
24 |
|
|
|
25 |
|
|
for (int reps = 0; reps < 2; ++reps) { |
26 |
|
|
ForkJoinPool g = procs == 0? new ForkJoinPool() : |
27 |
|
|
new ForkJoinPool(procs); |
28 |
|
|
lastStealCount = g.getStealCount(); |
29 |
|
|
for (int i = 0; i < 10; ++i) { |
30 |
|
|
test(g, num); |
31 |
|
|
} |
32 |
|
|
System.out.println(g); |
33 |
|
|
g.shutdown(); |
34 |
|
|
} |
35 |
|
|
} |
36 |
|
|
|
37 |
|
|
static void test(ForkJoinPool g, int num) throws Exception { |
38 |
|
|
int ps = g.getParallelism(); |
39 |
|
|
long start = System.currentTimeMillis(); |
40 |
|
|
DynamicLeftSpineFib f = new DynamicLeftSpineFib(num, null); |
41 |
|
|
g.invoke(f); |
42 |
|
|
long time = System.currentTimeMillis() - start; |
43 |
|
|
double secs = ((double)time) / 1000.0; |
44 |
|
|
long result = f.getAnswer(); |
45 |
|
|
System.out.print("DynamicLeftSpineFib " + num + " = " + result); |
46 |
|
|
System.out.printf("\tTime: %7.3f", secs); |
47 |
|
|
long sc = g.getStealCount(); |
48 |
|
|
long ns = sc - lastStealCount; |
49 |
|
|
lastStealCount = sc; |
50 |
|
|
System.out.printf(" Steals/t: %5d", ns/ps); |
51 |
|
|
System.out.printf(" Workers: %8d", g.getPoolSize()); |
52 |
|
|
System.out.println(); |
53 |
|
|
} |
54 |
|
|
|
55 |
|
|
|
56 |
|
|
// Initialized with argument; replaced with result |
57 |
|
|
int number; |
58 |
|
|
DynamicLeftSpineFib next; |
59 |
|
|
|
60 |
|
|
DynamicLeftSpineFib(int n, DynamicLeftSpineFib nxt) { |
61 |
|
|
number = n; next = nxt; |
62 |
|
|
} |
63 |
|
|
|
64 |
|
|
int getAnswer() { |
65 |
|
|
return number; |
66 |
|
|
} |
67 |
|
|
|
68 |
|
|
public final void compute() { |
69 |
|
|
int n = number; |
70 |
|
|
if (n > 1) { |
71 |
|
|
DynamicLeftSpineFib rt = null; |
72 |
|
|
while (n > 1 && getSurplusQueuedTaskCount() <= 3) { |
73 |
|
|
(rt = new DynamicLeftSpineFib(n - 2, rt)).fork(); |
74 |
|
|
n -= 1; |
75 |
|
|
} |
76 |
|
|
int r = seqFib(n); |
77 |
|
|
while (rt != null) { |
78 |
|
|
if (rt.tryUnfork()) rt.compute(); else rt.helpJoin(); |
79 |
|
|
r += rt.number; |
80 |
|
|
rt = rt.next; |
81 |
|
|
} |
82 |
|
|
number = r; |
83 |
|
|
} |
84 |
|
|
} |
85 |
|
|
|
86 |
|
|
// Sequential version for arguments less than threshold |
87 |
|
|
static int seqFib(int n) { |
88 |
|
|
if (n <= 1) |
89 |
|
|
return n; |
90 |
|
|
else |
91 |
|
|
return seqFib(n-1) + seqFib(n-2); |
92 |
|
|
} |
93 |
|
|
|
94 |
|
|
} |
95 |
|
|
|