151 lines
3.7 KiB
C
151 lines
3.7 KiB
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2015-2016 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#define _GNU_SOURCE
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#include <assert.h>
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#include <pthread.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <limits.h>
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/* How many threads fit in the target's thread number space. */
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long tid_max = -1;
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/* Number of threads spawned. */
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unsigned long thread_counter;
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/* How long it takes to spawn as many threads as fits in the thread
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number space. On systems where thread IDs are just monotonically
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incremented, this is enough for the tid numbers to wrap around. On
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targets that randomize thread IDs, this is enough time to give each
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number in the thread number space some chance of reuse. It'll be
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capped to a lower value if we can't compute it. */
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unsigned int reuse_time = -1;
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void *
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do_nothing_thread_func (void *arg)
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{
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usleep (1);
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return NULL;
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}
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void *
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spawner_thread_func (void *arg)
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{
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while (1)
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{
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pthread_t child;
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int rc;
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thread_counter++;
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rc = pthread_create (&child, NULL, do_nothing_thread_func, NULL);
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assert (rc == 0);
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rc = pthread_join (child, NULL);
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assert (rc == 0);
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}
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return NULL;
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}
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/* Called after the program is done counting number of spawned threads
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for a period, to compute REUSE_TIME. */
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void
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after_count (void)
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{
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}
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/* Called after enough time has passed for TID reuse to occur. */
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void
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after_reuse_time (void)
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{
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}
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#ifdef __linux__
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/* Get the running system's configured pid_max. */
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static int
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linux_proc_get_pid_max (void)
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{
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static const char filename[] ="/proc/sys/kernel/pid_max";
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FILE *file;
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char buf[100];
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int retval = -1;
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file = fopen (filename, "r");
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if (file == NULL)
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{
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fprintf (stderr, "unable to open %s\n", filename);
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return -1;
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}
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if (fgets (buf, sizeof (buf), file) != NULL)
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retval = strtol (buf, NULL, 10);
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fclose (file);
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return retval;
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}
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#endif
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int
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main (int argc, char *argv[])
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{
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pthread_t child;
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int rc;
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unsigned int reuse_time_raw = 0;
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rc = pthread_create (&child, NULL, spawner_thread_func, NULL);
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assert (rc == 0);
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#define COUNT_TIME 2
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sleep (COUNT_TIME);
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#ifdef __linux__
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tid_max = linux_proc_get_pid_max ();
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#endif
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/* If we don't know how many threads it would take to use the whole
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number space on this system, just run the test for a bit. */
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if (tid_max > 0)
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{
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reuse_time_raw = tid_max / ((float) thread_counter / COUNT_TIME) + 0.5;
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/* Give it a bit more, just in case. */
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reuse_time = reuse_time_raw + 3;
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}
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/* 4 seconds were sufficient on the machine this was first observed,
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an Intel i7-2620M @ 2.70GHz running Linux 3.18.7, with
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pid_max=32768. Going forward, as machines get faster, this will
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need less time, unless pid_max is set to a very high number. To
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avoid unreasonably long test time, cap to an upper bound. */
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if (reuse_time > 60)
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reuse_time = 60;
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printf ("thread_counter=%lu, tid_max = %ld, reuse_time_raw=%u, reuse_time=%u\n",
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thread_counter, tid_max, reuse_time_raw, reuse_time);
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after_count ();
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sleep (reuse_time);
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after_reuse_time ();
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return 0;
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}
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