glibc/support/xthread.h

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/* Support functionality for using threads.
Copyright (C) 2016-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
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<https://www.gnu.org/licenses/>. */
#ifndef SUPPORT_THREAD_H
#define SUPPORT_THREAD_H
#include <pthread.h>
#include <sys/cdefs.h>
__BEGIN_DECLS
/* Terminate the process (with exit status 0) after SECONDS have
elapsed, from a helper thread. The process is terminated with the
exit function, so atexit handlers are executed. */
void delayed_exit (int seconds);
/* Terminate the process (with exit status 1) if VALUE is not zero.
In that case, print a failure message to standard output mentioning
FUNCTION. The process is terminated with the exit function, so
atexit handlers are executed. */
void xpthread_check_return (const char *function, int value);
/* The following functions call the corresponding libpthread functions
and terminate the process on error. */
void xpthread_barrier_init (pthread_barrier_t *barrier,
pthread_barrierattr_t *attr, unsigned int count);
void xpthread_barrier_destroy (pthread_barrier_t *barrier);
void xpthread_barrierattr_destroy (pthread_barrierattr_t *);
void xpthread_barrierattr_init (pthread_barrierattr_t *);
void xpthread_barrierattr_setpshared (pthread_barrierattr_t *, int pshared);
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void xpthread_mutexattr_destroy (pthread_mutexattr_t *);
void xpthread_mutexattr_init (pthread_mutexattr_t *);
void xpthread_mutexattr_setprotocol (pthread_mutexattr_t *, int);
void xpthread_mutexattr_setpshared (pthread_mutexattr_t *, int);
void xpthread_mutexattr_setrobust (pthread_mutexattr_t *, int);
void xpthread_mutexattr_settype (pthread_mutexattr_t *, int);
void xpthread_mutex_init (pthread_mutex_t *, const pthread_mutexattr_t *);
void xpthread_mutex_destroy (pthread_mutex_t *);
void xpthread_mutex_lock (pthread_mutex_t *mutex);
void xpthread_mutex_unlock (pthread_mutex_t *mutex);
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void xpthread_mutex_consistent (pthread_mutex_t *);
void xpthread_spin_lock (pthread_spinlock_t *lock);
void xpthread_spin_unlock (pthread_spinlock_t *lock);
void xpthread_cond_wait (pthread_cond_t * cond, pthread_mutex_t * mutex);
pthread_t xpthread_create (pthread_attr_t *attr,
void *(*thread_func) (void *), void *closure);
void xpthread_detach (pthread_t thr);
void xpthread_cancel (pthread_t thr);
void *xpthread_join (pthread_t thr);
void xpthread_once (pthread_once_t *guard, void (*func) (void));
void xpthread_attr_destroy (pthread_attr_t *attr);
void xpthread_attr_init (pthread_attr_t *attr);
void xpthread_attr_setdetachstate (pthread_attr_t *attr,
int detachstate);
void xpthread_attr_setstack (pthread_attr_t *attr, void *stackaddr,
size_t stacksize);
void xpthread_attr_setstacksize (pthread_attr_t *attr,
size_t stacksize);
nptl: Invert the mmap/mprotect logic on allocated stacks (BZ#18988) Current allocate_stack logic for create stacks is to first mmap all the required memory with the desirable memory and then mprotect the guard area with PROT_NONE if required. Although it works as expected, it pessimizes the allocation because it requires the kernel to actually increase commit charge (it counts against the available physical/swap memory available for the system). The only issue is to actually check this change since side-effects are really Linux specific and to actually account them it would require a kernel specific tests to parse the system wide information. On the kernel I checked /proc/self/statm does not show any meaningful difference for vmm and/or rss before and after thread creation. I could only see really meaningful information checking on system wide /proc/meminfo between thread creation: MemFree, MemAvailable, and Committed_AS shows large difference without the patch. I think trying to use these kind of information on a testcase is fragile. The BZ#18988 reports shows that the commit pages are easily seen with mlockall (MCL_FUTURE) (with lock all pages that become mapped in the process) however a more straighfoward testcase shows that pthread_create could be faster using this patch: -- static const int inner_count = 256; static const int outer_count = 128; static void *thread1(void *arg) { return NULL; } static void *sleeper(void *arg) { pthread_t ts[inner_count]; for (int i = 0; i < inner_count; i++) pthread_create (&ts[i], &a, thread1, NULL); for (int i = 0; i < inner_count; i++) pthread_join (ts[i], NULL); return NULL; } int main(void) { pthread_attr_init(&a); pthread_attr_setguardsize(&a, 1<<20); pthread_attr_setstacksize(&a, 1134592); pthread_t ts[outer_count]; for (int i = 0; i < outer_count; i++) pthread_create(&ts[i], &a, sleeper, NULL); for (int i = 0; i < outer_count; i++) pthread_join(ts[i], NULL); assert(r == 0); } return 0; } -- On x86_64 (4.4.0-45-generic, gcc 5.4.0) running the small benchtests I see: $ time ./test real 0m3.647s user 0m0.080s sys 0m11.836s While with the patch I see: $ time ./test real 0m0.696s user 0m0.040s sys 0m1.152s So I added a pthread_create benchtest (thread_create) which check the thread creation latency. As for the simple benchtests, I saw improvements in thread creation on all architectures I tested the change. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. [BZ #18988] * benchtests/thread_create-inputs: New file. * benchtests/thread_create-source.c: Likewise. * support/xpthread_attr_setguardsize.c: Likewise. * support/Makefile (libsupport-routines): Add xpthread_attr_setguardsize object. * support/xthread.h: Add xpthread_attr_setguardsize prototype. * benchtests/Makefile (bench-pthread): Add thread_create. * nptl/allocatestack.c (allocate_stack): Call mmap with PROT_NONE and then mprotect the required area.
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void xpthread_attr_setguardsize (pthread_attr_t *attr,
size_t guardsize);
/* Return the stack size used on support_set_small_thread_stack_size. */
size_t support_small_thread_stack_size (void);
/* Set the stack size in ATTR to a small value, but still large enough
to cover most internal glibc stack usage. */
void support_set_small_thread_stack_size (pthread_attr_t *attr);
/* Return a pointer to a thread attribute which requests a small
stack. The caller must not free this pointer. */
pthread_attr_t *support_small_stack_thread_attribute (void);
/* This function returns non-zero if pthread_barrier_wait returned
PTHREAD_BARRIER_SERIAL_THREAD. */
int xpthread_barrier_wait (pthread_barrier_t *barrier);
void xpthread_rwlock_init (pthread_rwlock_t *rwlock,
const pthread_rwlockattr_t *attr);
void xpthread_rwlockattr_init (pthread_rwlockattr_t *attr);
void xpthread_rwlockattr_setkind_np (pthread_rwlockattr_t *attr, int pref);
void xpthread_rwlock_wrlock (pthread_rwlock_t *rwlock);
void xpthread_rwlock_rdlock (pthread_rwlock_t *rwlock);
void xpthread_rwlock_unlock (pthread_rwlock_t *rwlock);
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void xpthread_rwlock_destroy (pthread_rwlock_t *rwlock);
pthread_key_t xpthread_key_create (void (*destr_function) (void *));
void xpthread_key_delete (pthread_key_t key);
__END_DECLS
#endif /* SUPPORT_THREAD_H */