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nptl: Eliminate <smp.h> and __is_smp 

Most systems are SMP, so optimizing for the UP case is no longer
approriate.  A dynamic check based on the kernel identification
has been only implemented for i386 anyway.

To disable adaptive mutexes on sh, define DEFAULT_ADAPTIVE_COUNT
as zero for this architecture.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2020-11-13 15:19:41 +01:00
parent d5c4cce9c3
commit 26f7c72a99
9 changed files with 20 additions and 121 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
nptl/nptl-init.c
View File

@ -32,7 +32,6 @@
#include <fork.h>
#include <version.h>
#include <shlib-compat.h>
#include <smp.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <kernel-features.h>
@ -346,9 +345,6 @@ __pthread_initialize_minimal_internal (void)
__libc_pthread_init (&__fork_generation, __reclaim_stacks,
ptr_pthread_functions);
/* Determine whether the machine is SMP or not. */
__is_smp = is_smp_system ();
#if HAVE_TUNABLES
__pthread_tunables_init ();
#endif

3
nptl/pthreadP.h
View File

@ -208,9 +208,6 @@ extern void __default_pthread_attr_freeres (void) attribute_hidden;
extern size_t __static_tls_size attribute_hidden;
extern size_t __static_tls_align_m1 attribute_hidden;
/* Flag whether the machine is SMP or not. */
extern int __is_smp attribute_hidden;
/* Thread descriptor handling. */
extern list_t __stack_user;
hidden_proto (__stack_user)

3
nptl/pthread_mutex_lock.c
View File

@ -120,9 +120,6 @@ __pthread_mutex_lock (pthread_mutex_t *mutex)
else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex)
== PTHREAD_MUTEX_ADAPTIVE_NP, 1))
{
if (! __is_smp)
goto simple;
if (LLL_MUTEX_TRYLOCK (mutex) != 0)
{
int cnt = 0;

3
nptl/pthread_mutex_timedlock.c
View File

@ -113,9 +113,6 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
case PTHREAD_MUTEX_ADAPTIVE_NP:
if (! __is_smp)
goto simple;
if (lll_trylock (mutex->__data.__lock) != 0)
{
int cnt = 0;

27
nptl/smp.h
View File

@ -1,27 +0,0 @@
/* Determine whether the host has multiple processors. Stub version.
Copyright (C) 1996-2020 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
/* Test whether the machine has more than one processor. This is not the
best test but good enough. More complicated tests would require `malloc'
which is not available at that time. */
static inline int
is_smp_system (void)
{
/* Assume all machines are SMP and/or CMT and/or SMT. */
return 1;
}

3
nptl/vars.c
View File

@ -27,9 +27,6 @@ union pthread_attr_transparent __default_pthread_attr attribute_hidden;
/* Mutex protecting __default_pthread_attr. */
int __default_pthread_attr_lock = LLL_LOCK_INITIALIZER;
/* Flag whether the machine is SMP or not. */
int __is_smp attribute_hidden;
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
/* Variable set to a nonzero value either if more than one thread runs or ran,
or if a single-threaded process is trying to cancel itself. See

55
sysdeps/unix/sysv/linux/i386/smp.h
View File

@ -1,55 +0,0 @@
/* Determine whether the host has multiple processors. Linux version.
Copyright (C) 1996-2020 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/utsname.h>
#include <not-cancel.h>
/* Test whether the machine has more than one processor. This is not the
best test but good enough. More complicated tests would require `malloc'
which is not available at that time. */
static inline int
is_smp_system (void)
{
union
{
struct utsname uts;
char buf[512];
} u;
char *cp;
/* Try reading the number using `sysctl' first. */
if (__uname (&u.uts) == 0)
cp = u.uts.version;
else
{
/* This was not successful. Now try reading the /proc filesystem. */
int fd = __open64_nocancel ("/proc/sys/kernel/version", O_RDONLY);
if (__builtin_expect (fd, 0) == -1
|| __read_nocancel (fd, u.buf, sizeof (u.buf)) <= 0)
/* This also didn't work. We give up and say it's a UP machine. */
u.buf[0] = '\0';
__close_nocancel_nostatus (fd);
cp = u.buf;
}
return strstr (cp, "SMP") != NULL;
}

20
sysdeps/unix/sysv/linux/sh/adaptive_spin_count.h Normal file
View File

@ -0,0 +1,20 @@
/* Maximum adaptive spin count default for sh.
Copyright (C) 2020 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
<https://www.gnu.org/licenses/>. */
/* Disable spinning because sh is always uniprocessor. */
#define DEFAULT_ADAPTIVE_COUNT 0

23
sysdeps/unix/sysv/linux/sh/smp.h
View File

@ -1,23 +0,0 @@
/* Determine whether the host has multiple processors. SH version.
Copyright (C) 2002-2020 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
static inline int
is_smp_system (void)
{
return 0;
}