1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
(defglobal *counter* 0)
(declaim (fixnum *counter*))
;; how many threads to make, not all at once, of course
(defparameter howmany-threads 20000)
(defun thread-lambda ()
(atomic-incf *counter*))
(defun test1 (&optional (n howmany-threads))
(setq *counter* 0)
(dotimes (i n)
(sb-thread:join-thread (sb-thread:make-thread #'thread-lambda)))
(assert (= *counter* n)))
(defun test2 (&optional (n howmany-threads))
(setq *counter* 0)
(let (prev-thread)
(dotimes (i n)
;; while starting the new thread, join the previously made.
(let ((new-thread (sb-thread:make-thread #'thread-lambda)))
(when prev-thread
(sb-thread:join-thread prev-thread))
(setq prev-thread new-thread)))
(sb-thread:join-thread prev-thread))
(assert (= *counter* n)))
(defun test3 (&optional (n howmany-threads))
(setq *counter* 0)
;; try making 10 at a time and waiting for those 10 before making more
(dotimes (i (/ n 10))
(let ((threads))
(dotimes (i 10)
(push (sb-thread:make-thread #'thread-lambda) threads))
(dolist (thread threads)
(sb-thread:join-thread thread))))
(assert (= *counter* n)))
Without :pauseless-threadstart
-------------------------------
$ perf stat ... --eval '(test1)' --quit
6,435.72 msec task-clock:u # 1.103 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
219,735 page-faults:u # 0.034 M/sec
1,484,016,696 cycles:u # 0.231 GHz
17,008,247,359 stalled-cycles-frontend:u # 1146.10% frontend cycles idle
525,232,002 instructions:u # 0.35 insn per cycle
# 32.38 stalled cycles per insn
145,098,224 branches:u # 22.546 M/sec
4,045,481 branch-misses:u # 2.79% of all branches
5.834005191 seconds time elapsed
0.684522000 seconds user
6.391622000 seconds sys
$ perf stat ... --eval '(test2)' --quit
6,383.26 msec task-clock:u # 1.182 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
220,625 page-faults:u # 0.035 M/sec
1,435,852,231 cycles:u # 0.225 GHz
16,839,228,290 stalled-cycles-frontend:u # 1172.77% frontend cycles idle
524,776,029 instructions:u # 0.37 insn per cycle
# 32.09 stalled cycles per insn
144,951,979 branches:u # 22.708 M/sec
4,018,908 branch-misses:u # 2.77% of all branches
5.401308431 seconds time elapsed
0.773771000 seconds user
6.235207000 seconds sys
$ perf stat ... --eval '(test3)' --quit
7,813.04 msec task-clock:u # 1.133 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
131,699 page-faults:u # 0.017 M/sec
1,477,424,012 cycles:u # 0.189 GHz
20,769,787,623 stalled-cycles-frontend:u # 1405.81% frontend cycles idle
525,748,318 instructions:u # 0.36 insn per cycle
# 39.51 stalled cycles per insn
145,134,345 branches:u # 18.576 M/sec
4,412,369 branch-misses:u # 3.04% of all branches
6.894458409 seconds time elapsed
0.641120000 seconds user
7.864134000 seconds sys
Conclusion: approximately 300 microseconds to start a thread
With :pauseless-threadstart
----------------------------
$ perf stat ... --eval '(test1)' --quit
1,541.91 msec task-clock:u # 1.068 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
633 page-faults:u # 0.411 K/sec
801,317,853 cycles:u # 0.520 GHz
3,751,130,586 stalled-cycles-frontend:u # 468.12% frontend cycles idle
352,170,311 instructions:u # 0.44 insn per cycle
# 10.65 stalled cycles per insn
81,884,155 branches:u # 53.106 M/sec
1,334,916 branch-misses:u # 1.63% of all branches
1.443664147 seconds time elapsed
0.425407000 seconds user
1.471034000 seconds sys
$ perf stat ... --eval '(test2)' --quit
1,249.01 msec task-clock:u # 1.550 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
573 page-faults:u # 0.459 K/sec
668,480,325 cycles:u # 0.535 GHz
3,086,418,550 stalled-cycles-frontend:u # 461.71% frontend cycles idle
376,966,208 instructions:u # 0.56 insn per cycle
# 8.19 stalled cycles per insn
95,790,671 branches:u # 76.694 M/sec
918,120 branch-misses:u # 0.96% of all branches
0.805563424 seconds time elapsed
0.325539000 seconds user
1.162641000 seconds sys
$ perf stat ... --eval '(test3)' --quit
1,308.09 msec task-clock:u # 1.455 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
4,838 page-faults:u # 0.004 M/sec
660,514,151 cycles:u # 0.505 GHz
3,230,465,234 stalled-cycles-frontend:u # 489.08% frontend cycles idle
364,307,811 instructions:u # 0.55 insn per cycle
# 8.87 stalled cycles per insn
92,966,084 branches:u # 71.070 M/sec
730,714 branch-misses:u # 0.79% of all branches
0.899161220 seconds time elapsed
0.339090000 seconds user
1.227741000 seconds sys
Conclusion: 40 to 100 microseconds to start a thread
|
