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4eec2deb PA |
1 | /* This testcase is part of GDB, the GNU debugger. |
2 | ||
1d506c26 | 3 | Copyright 2015-2024 Free Software Foundation, Inc. |
4eec2deb PA |
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> | |
7a81c1e2 | 24 | #include <string.h> |
4eec2deb PA |
25 | #include <limits.h> |
26 | ||
27 | /* How many threads fit in the target's thread number space. */ | |
28 | long tid_max = -1; | |
29 | ||
30 | /* Number of threads spawned. */ | |
31 | unsigned long thread_counter; | |
32 | ||
33 | /* How long it takes to spawn as many threads as fits in the thread | |
34 | number space. On systems where thread IDs are just monotonically | |
35 | incremented, this is enough for the tid numbers to wrap around. On | |
36 | targets that randomize thread IDs, this is enough time to give each | |
37 | number in the thread number space some chance of reuse. It'll be | |
7a81c1e2 PW |
38 | capped to a lower value if we can't compute it. REUSE_TIME_CAP |
39 | is the max value, and the default value if ever the program | |
40 | has problem to compute it. */ | |
41 | #define REUSE_TIME_CAP 60 | |
42 | unsigned int reuse_time = REUSE_TIME_CAP; | |
4eec2deb PA |
43 | |
44 | void * | |
45 | do_nothing_thread_func (void *arg) | |
46 | { | |
47 | usleep (1); | |
48 | return NULL; | |
49 | } | |
50 | ||
7a81c1e2 PW |
51 | static void |
52 | check_rc (int rc, const char *what) | |
53 | { | |
54 | if (rc != 0) | |
55 | { | |
56 | fprintf (stderr, "unexpected error from %s: %s (%d)\n", | |
57 | what, strerror (rc), rc); | |
58 | assert (0); | |
59 | } | |
60 | } | |
61 | ||
4eec2deb PA |
62 | void * |
63 | spawner_thread_func (void *arg) | |
64 | { | |
65 | while (1) | |
66 | { | |
67 | pthread_t child; | |
68 | int rc; | |
69 | ||
70 | thread_counter++; | |
71 | ||
72 | rc = pthread_create (&child, NULL, do_nothing_thread_func, NULL); | |
7a81c1e2 | 73 | check_rc (rc, "pthread_create"); |
4eec2deb PA |
74 | |
75 | rc = pthread_join (child, NULL); | |
7a81c1e2 | 76 | check_rc (rc, "pthread_join"); |
4eec2deb PA |
77 | } |
78 | ||
79 | return NULL; | |
80 | } | |
81 | ||
82 | /* Called after the program is done counting number of spawned threads | |
83 | for a period, to compute REUSE_TIME. */ | |
84 | ||
85 | void | |
86 | after_count (void) | |
87 | { | |
88 | } | |
89 | ||
90 | /* Called after enough time has passed for TID reuse to occur. */ | |
91 | ||
92 | void | |
93 | after_reuse_time (void) | |
94 | { | |
95 | } | |
96 | ||
97 | #ifdef __linux__ | |
98 | ||
99 | /* Get the running system's configured pid_max. */ | |
100 | ||
101 | static int | |
102 | linux_proc_get_pid_max (void) | |
103 | { | |
104 | static const char filename[] ="/proc/sys/kernel/pid_max"; | |
105 | FILE *file; | |
106 | char buf[100]; | |
107 | int retval = -1; | |
108 | ||
109 | file = fopen (filename, "r"); | |
110 | if (file == NULL) | |
111 | { | |
112 | fprintf (stderr, "unable to open %s\n", filename); | |
113 | return -1; | |
114 | } | |
115 | ||
116 | if (fgets (buf, sizeof (buf), file) != NULL) | |
117 | retval = strtol (buf, NULL, 10); | |
118 | ||
119 | fclose (file); | |
120 | return retval; | |
121 | } | |
122 | ||
123 | #endif | |
124 | ||
125 | int | |
126 | main (int argc, char *argv[]) | |
127 | { | |
128 | pthread_t child; | |
129 | int rc; | |
130 | unsigned int reuse_time_raw = 0; | |
131 | ||
132 | rc = pthread_create (&child, NULL, spawner_thread_func, NULL); | |
7a81c1e2 | 133 | check_rc (rc, "pthread_create spawner_thread"); |
4eec2deb PA |
134 | |
135 | #define COUNT_TIME 2 | |
136 | sleep (COUNT_TIME); | |
137 | ||
138 | #ifdef __linux__ | |
139 | tid_max = linux_proc_get_pid_max (); | |
140 | #endif | |
141 | /* If we don't know how many threads it would take to use the whole | |
142 | number space on this system, just run the test for a bit. */ | |
143 | if (tid_max > 0) | |
144 | { | |
145 | reuse_time_raw = tid_max / ((float) thread_counter / COUNT_TIME) + 0.5; | |
146 | ||
147 | /* Give it a bit more, just in case. */ | |
148 | reuse_time = reuse_time_raw + 3; | |
149 | } | |
150 | ||
151 | /* 4 seconds were sufficient on the machine this was first observed, | |
152 | an Intel i7-2620M @ 2.70GHz running Linux 3.18.7, with | |
153 | pid_max=32768. Going forward, as machines get faster, this will | |
154 | need less time, unless pid_max is set to a very high number. To | |
155 | avoid unreasonably long test time, cap to an upper bound. */ | |
7a81c1e2 PW |
156 | if (reuse_time > REUSE_TIME_CAP) |
157 | reuse_time = REUSE_TIME_CAP; | |
4eec2deb PA |
158 | printf ("thread_counter=%lu, tid_max = %ld, reuse_time_raw=%u, reuse_time=%u\n", |
159 | thread_counter, tid_max, reuse_time_raw, reuse_time); | |
160 | after_count (); | |
161 | ||
162 | sleep (reuse_time); | |
163 | ||
164 | after_reuse_time (); | |
165 | return 0; | |
166 | } |