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4eec2deb PA |
1 | /* This testcase is part of GDB, the GNU debugger. |
2 | ||
3 | Copyright 2015 Free Software Foundation, Inc. | |
4 | ||
5 | This program is free software; you can redistribute it and/or modify | |
6 | it under the terms of the GNU General Public License as published by | |
7 | the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
17 | ||
18 | #define _GNU_SOURCE | |
19 | #include <assert.h> | |
20 | #include <pthread.h> | |
21 | #include <stdlib.h> | |
22 | #include <unistd.h> | |
23 | #include <stdio.h> | |
24 | #include <limits.h> | |
25 | ||
26 | /* How many threads fit in the target's thread number space. */ | |
27 | long tid_max = -1; | |
28 | ||
29 | /* Number of threads spawned. */ | |
30 | unsigned long thread_counter; | |
31 | ||
32 | /* How long it takes to spawn as many threads as fits in the thread | |
33 | number space. On systems where thread IDs are just monotonically | |
34 | incremented, this is enough for the tid numbers to wrap around. On | |
35 | targets that randomize thread IDs, this is enough time to give each | |
36 | number in the thread number space some chance of reuse. It'll be | |
37 | capped to a lower value if we can't compute it. */ | |
38 | unsigned int reuse_time = -1; | |
39 | ||
40 | void * | |
41 | do_nothing_thread_func (void *arg) | |
42 | { | |
43 | usleep (1); | |
44 | return NULL; | |
45 | } | |
46 | ||
47 | void * | |
48 | spawner_thread_func (void *arg) | |
49 | { | |
50 | while (1) | |
51 | { | |
52 | pthread_t child; | |
53 | int rc; | |
54 | ||
55 | thread_counter++; | |
56 | ||
57 | rc = pthread_create (&child, NULL, do_nothing_thread_func, NULL); | |
58 | assert (rc == 0); | |
59 | ||
60 | rc = pthread_join (child, NULL); | |
61 | assert (rc == 0); | |
62 | } | |
63 | ||
64 | return NULL; | |
65 | } | |
66 | ||
67 | /* Called after the program is done counting number of spawned threads | |
68 | for a period, to compute REUSE_TIME. */ | |
69 | ||
70 | void | |
71 | after_count (void) | |
72 | { | |
73 | } | |
74 | ||
75 | /* Called after enough time has passed for TID reuse to occur. */ | |
76 | ||
77 | void | |
78 | after_reuse_time (void) | |
79 | { | |
80 | } | |
81 | ||
82 | #ifdef __linux__ | |
83 | ||
84 | /* Get the running system's configured pid_max. */ | |
85 | ||
86 | static int | |
87 | linux_proc_get_pid_max (void) | |
88 | { | |
89 | static const char filename[] ="/proc/sys/kernel/pid_max"; | |
90 | FILE *file; | |
91 | char buf[100]; | |
92 | int retval = -1; | |
93 | ||
94 | file = fopen (filename, "r"); | |
95 | if (file == NULL) | |
96 | { | |
97 | fprintf (stderr, "unable to open %s\n", filename); | |
98 | return -1; | |
99 | } | |
100 | ||
101 | if (fgets (buf, sizeof (buf), file) != NULL) | |
102 | retval = strtol (buf, NULL, 10); | |
103 | ||
104 | fclose (file); | |
105 | return retval; | |
106 | } | |
107 | ||
108 | #endif | |
109 | ||
110 | int | |
111 | main (int argc, char *argv[]) | |
112 | { | |
113 | pthread_t child; | |
114 | int rc; | |
115 | unsigned int reuse_time_raw = 0; | |
116 | ||
117 | rc = pthread_create (&child, NULL, spawner_thread_func, NULL); | |
118 | assert (rc == 0); | |
119 | ||
120 | #define COUNT_TIME 2 | |
121 | sleep (COUNT_TIME); | |
122 | ||
123 | #ifdef __linux__ | |
124 | tid_max = linux_proc_get_pid_max (); | |
125 | #endif | |
126 | /* If we don't know how many threads it would take to use the whole | |
127 | number space on this system, just run the test for a bit. */ | |
128 | if (tid_max > 0) | |
129 | { | |
130 | reuse_time_raw = tid_max / ((float) thread_counter / COUNT_TIME) + 0.5; | |
131 | ||
132 | /* Give it a bit more, just in case. */ | |
133 | reuse_time = reuse_time_raw + 3; | |
134 | } | |
135 | ||
136 | /* 4 seconds were sufficient on the machine this was first observed, | |
137 | an Intel i7-2620M @ 2.70GHz running Linux 3.18.7, with | |
138 | pid_max=32768. Going forward, as machines get faster, this will | |
139 | need less time, unless pid_max is set to a very high number. To | |
140 | avoid unreasonably long test time, cap to an upper bound. */ | |
141 | if (reuse_time > 60) | |
142 | reuse_time = 60; | |
143 | printf ("thread_counter=%lu, tid_max = %ld, reuse_time_raw=%u, reuse_time=%u\n", | |
144 | thread_counter, tid_max, reuse_time_raw, reuse_time); | |
145 | after_count (); | |
146 | ||
147 | sleep (reuse_time); | |
148 | ||
149 | after_reuse_time (); | |
150 | return 0; | |
151 | } |