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Stefan Liebler 12d2dd7060 Optimize generic spinlock code and use C11 like atomic macros.
This patch optimizes the generic spinlock code.

The type pthread_spinlock_t is a typedef to volatile int on all archs.
Passing a volatile pointer to the atomic macros which are not mapped to the
C11 atomic builtins can lead to extra stores and loads to stack if such
a macro creates a temporary variable by using "__typeof (*(mem)) tmp;".
Thus, those macros which are used by spinlock code - atomic_exchange_acquire,
atomic_load_relaxed, atomic_compare_exchange_weak - have to be adjusted.
According to the comment from  Szabolcs Nagy, the type of a cast expression is
unqualified (see http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_423.htm):
__typeof ((__typeof (*(mem)) *(mem)) tmp;
Thus from spinlock perspective the variable tmp is of type int instead of
type volatile int.  This patch adjusts those macros in include/atomic.h.
With this construct GCC >= 5 omits the extra stores and loads.

The atomic macros are replaced by the C11 like atomic macros and thus
the code is aligned to it.  The pthread_spin_unlock implementation is now
using release memory order instead of sequentially consistent memory order.
The issue with passed volatile int pointers applies to the C11 like atomic
macros as well as the ones used before.

I've added a glibc_likely hint to the first atomic exchange in
pthread_spin_lock in order to return immediately to the caller if the lock is
free.  Without the hint, there is an additional jump if the lock is free.

I've added the atomic_spin_nop macro within the loop of plain reads.
The plain reads are also realized by C11 like atomic_load_relaxed macro.

The new define ATOMIC_EXCHANGE_USES_CAS determines if the first try to acquire
the spinlock in pthread_spin_lock or pthread_spin_trylock is an exchange
or a CAS.  This is defined in atomic-machine.h for all architectures.

The define SPIN_LOCK_READS_BETWEEN_CMPXCHG is now removed.
There is no technical reason for throwing in a CAS every now and then,
and so far we have no evidence that it can improve performance.
If that would be the case, we have to adjust other spin-waiting loops
elsewhere, too!  Using a CAS loop without plain reads is not a good idea
on many targets and wasn't used by one.  Thus there is now no option to
do so.

Architectures are now using the generic spinlock automatically if they
do not provide an own implementation.  Thus the pthread_spin_lock.c files
in sysdeps folder are deleted.

ChangeLog:

	* NEWS: Mention new spinlock implementation.
	* include/atomic.h:
	(__atomic_val_bysize): Cast type to omit volatile qualifier.
	(atomic_exchange_acq): Likewise.
	(atomic_load_relaxed): Likewise.
	(ATOMIC_EXCHANGE_USES_CAS): Check definition.
	* nptl/pthread_spin_init.c (pthread_spin_init):
	Use atomic_store_relaxed.
	* nptl/pthread_spin_lock.c (pthread_spin_lock):
	Use C11-like atomic macros.
	* nptl/pthread_spin_trylock.c (pthread_spin_trylock):
	Likewise.
	* nptl/pthread_spin_unlock.c (pthread_spin_unlock):
	Use atomic_store_release.
	* sysdeps/aarch64/nptl/pthread_spin_lock.c: Delete File.
	* sysdeps/arm/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/hppa/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/m68k/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/microblaze/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/mips/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/nios2/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/aarch64/atomic-machine.h (ATOMIC_EXCHANGE_USES_CAS): Define.
	* sysdeps/alpha/atomic-machine.h: Likewise.
	* sysdeps/arm/atomic-machine.h: Likewise.
	* sysdeps/i386/atomic-machine.h: Likewise.
	* sysdeps/ia64/atomic-machine.h: Likewise.
	* sysdeps/m68k/coldfire/atomic-machine.h: Likewise.
	* sysdeps/m68k/m680x0/m68020/atomic-machine.h: Likewise.
	* sysdeps/microblaze/atomic-machine.h: Likewise.
	* sysdeps/mips/atomic-machine.h: Likewise.
	* sysdeps/powerpc/powerpc32/atomic-machine.h: Likewise.
	* sysdeps/powerpc/powerpc64/atomic-machine.h: Likewise.
	* sysdeps/s390/atomic-machine.h: Likewise.
	* sysdeps/sparc/sparc32/atomic-machine.h: Likewise.
	* sysdeps/sparc/sparc32/sparcv9/atomic-machine.h: Likewise.
	* sysdeps/sparc/sparc64/atomic-machine.h: Likewise.
	* sysdeps/tile/tilegx/atomic-machine.h: Likewise.
	* sysdeps/tile/tilepro/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/hppa/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/nios2/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/sh/atomic-machine.h: Likewise.
	* sysdeps/x86_64/atomic-machine.h: Likewise.
2017-06-06 09:41:56 +02:00
argp Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
assert Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
benchtests benchtests: Add more tests for memrchr 2017-06-04 09:45:09 -07:00
bits Define SIG_HOLD for XPG4 (bug 21538). 2017-06-05 10:19:03 +00:00
catgets Update copyright dates not handled by scripts/update-copyrights. 2017-01-01 00:26:24 +00:00
conform conformtest: Correct signal.h expectations for XPG4 / XPG42. 2017-06-01 17:17:43 +00:00
crypt Add missing header files throughout the testsuite. 2017-02-16 17:33:18 -05:00
csu Delay initialization of CPU features struct in static binaries 2017-05-31 06:38:33 +05:30
ctype Remove C++ namespace handling from glibc headers. 2017-03-16 13:31:57 +00:00
debug Fix struct sigaltstack namespace (bug 21517). 2017-06-05 10:17:46 +00:00
dirent support: Prevent multiple deletion of temporary files 2017-05-08 16:20:40 +02:00
dlfcn Miscellaneous low-risk changes preparing for _ISOMAC testsuite. 2017-03-01 20:32:50 -05:00
elf Make __tunables_init hidden and avoid PLT 2017-05-25 06:55:58 -07:00
gmon Assume that O_NOFOLLOW is always defined 2017-04-13 21:28:18 +02:00
gnulib Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
grp Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
gshadow Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
hesiod Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
hurd Fix struct sigaltstack namespace (bug 21517). 2017-06-05 10:17:46 +00:00
iconv Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
iconvdata Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
include Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
inet Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
intl Suppress internal declarations for most of the testsuite. 2017-05-11 19:27:59 -04:00
io Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
libidn Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
libio libio: Avoid dup already opened file descriptor [BZ#21393] 2017-05-22 18:13:35 -03:00
locale Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
localedata Bug 20686: Add el_GR@euro support. 2017-05-03 15:37:04 -04:00
login Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
mach Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
malloc Add internal facility for dynamic array handling 2017-06-02 11:59:28 +02:00
manual manual: Provide consistent errno documentation. 2017-06-02 13:49:20 -07:00
math float128: Add wrappers to override ldbl-128 as float128. 2017-05-25 09:01:37 -03:00
mathvec Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
misc posix: Add missing build flags for p{write,read}v2 2017-06-02 11:12:29 -03:00
nis Include shlib-compat.h in many sunrpc/nis source files. 2017-06-04 11:31:28 -04:00
nptl Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
nptl_db Narrowing the visibility of libc-internal.h even further. 2017-03-01 20:33:46 -05:00
nscd Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
nss Suppress internal declarations for most of the testsuite. 2017-05-11 19:27:59 -04:00
po Add target to incorporate translations from translations.org 2017-01-20 12:32:46 +05:30
posix Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
pwd Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
resolv Include shlib-compat.h in many sunrpc/nis source files. 2017-06-04 11:31:28 -04:00
resource Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
rt Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
scripts Also create and use ldbl-compat-choose.h. 2017-05-19 11:30:26 +00:00
setjmp Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
shadow Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
signal Fix struct sigaltstack namespace (bug 21517). 2017-06-05 10:17:46 +00:00
socket Remove __need macros from signal.h. 2017-05-20 19:04:43 -04:00
soft-fp Narrowing the visibility of libc-internal.h even further. 2017-03-01 20:33:46 -05:00
stdio-common vfprintf.c: Refactor magic number 32 into EXTSIZ. 2017-05-08 16:13:16 -04:00
stdlib Include sys/param.h in stdlib/gmp-impl.h instead of redefining MAX/MIN 2017-06-01 20:44:22 -03:00
streams Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
string Add memchr tests for n == 0 2017-05-25 11:38:01 -07:00
sunrpc Include shlib-compat.h in many sunrpc/nis source files. 2017-06-04 11:31:28 -04:00
support resolv: Tests for various versions of res_init 2017-06-02 15:50:36 +02:00
sysdeps Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
sysvipc Fix test-sysvsem on some platforms 2017-01-02 18:53:50 -02:00
termios Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
time Remove C++ namespace handling from glibc headers. 2017-03-16 13:31:57 +00:00
timezone Add missing header files throughout the testsuite. 2017-02-16 17:33:18 -05:00
wcsmbs Do not use wildcard symbol names for public versions in Versions files. 2017-04-20 20:35:21 +00:00
wctype Remove C++ namespace handling from glibc headers. 2017-03-16 13:31:57 +00:00
.gitattributes Assume __NR_openat is always defined 2016-03-23 23:35:08 +01:00
.gitignore Add *.pyc to .gitignore 2015-05-18 15:26:26 +05:30
abi-tags Remove the bulk of the NaCl port. 2017-05-20 08:09:10 -04:00
aclocal.m4 Work even with compilers which enable -fstack-protector by default [BZ #7065] 2016-12-26 10:10:58 +01:00
BUGS [BZ #5222] 2007-10-28 08:24:07 +00:00
ChangeLog Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
ChangeLog.1 * Makefile (distribute): Add ChangeLog.[0-9]. 1995-04-14 03:52:54 +00:00
ChangeLog.2 * Makefile (distribute): Add ChangeLog.[0-9]. 1995-04-14 03:52:54 +00:00
ChangeLog.3 * Makefile (distribute): Add ChangeLog.[0-9]. 1995-04-14 03:52:54 +00:00
ChangeLog.4 * Makefile (distribute): Add ChangeLog.[0-9]. 1995-04-14 03:52:54 +00:00
ChangeLog.5 * sysdeps/posix/getaddrinfo.c: Implement configuration file 2006-05-04 06:38:07 +00:00
ChangeLog.6 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.7 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.8 ChangeLog: change Winblowz to Windows 2016-08-10 00:49:28 +08:00
ChangeLog.9 Update. 2000-04-28 06:14:43 +00:00
ChangeLog.10 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.11 ChangeLog: change Winblowz to Windows 2016-08-10 00:49:28 +08:00
ChangeLog.12 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.13 Update. 2002-10-03 16:37:04 +00:00
ChangeLog.14 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.15 Split out ChangeLog.15 at 2.3 branch point 2005-02-16 07:34:17 +00:00
ChangeLog.16 Fix typo in name 2012-06-21 16:45:27 +02:00
ChangeLog.17 Revert "Sun agreed to a change of the license for the RPC code to a BSD-like license." 2010-06-27 19:34:03 -07:00
ChangeLog.old-ports Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-aarch64 Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-aix Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-alpha ChangeLog: fix BZ style to be consistent and match majority of existing code 2017-04-03 15:18:07 -04:00
ChangeLog.old-ports-am33 Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-arm Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-cris Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-hppa ChangeLog: fix BZ style to be consistent and match majority of existing code 2017-04-03 15:18:07 -04:00
ChangeLog.old-ports-ia64 Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-linux-generic Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-m68k Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-microblaze Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-mips ChangeLog: fix BZ style to be consistent and match majority of existing code 2017-04-03 15:18:07 -04:00
ChangeLog.old-ports-powerpc Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-tile Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
config.h.in Suppress internal declarations for most of the testsuite. 2017-05-11 19:27:59 -04:00
config.make.in Deprecate libnsl by default (only shared library will be 2017-03-21 15:14:27 +01:00
configure Deprecate libnsl by default (only shared library will be 2017-03-21 15:14:27 +01:00
configure.ac Deprecate libnsl by default (only shared library will be 2017-03-21 15:14:27 +01:00
CONFORMANCE Move __STDC_* predefined macros from features.h to stdc-predef.h. 2012-02-22 12:53:04 +00:00
COPYING Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
COPYING.LIB Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
extra-lib.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
gen-locales.mk Split locale generation snippet into a separate file 2015-05-13 13:05:28 +05:30
INSTALL Assume that accept4 is always available and works 2017-04-19 07:44:48 +02:00
libc-abis A few more archs have IFUNC support. 2010-03-17 02:43:12 -07:00
libof-iterator.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
LICENSES Expand LICENSES file. 2012-12-05 21:56:15 +00:00
MAINTAINERS Add MAINTAINERS 2017-05-11 13:38:30 -04:00
Makeconfig Support dl-tunables.list in subdirectories 2017-05-25 05:41:18 -07:00
Makefile Suppress internal declarations for most of the testsuite. 2017-05-11 19:27:59 -04:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules Also create and use ldbl-compat-choose.h. 2017-05-19 11:30:26 +00:00
NAMESPACE Add and update many more entries. 2000-03-20 00:42:58 +00:00
NEWS Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
o-iterator.mk Fri Mar 17 12:58:37 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> 1995-03-17 18:42:51 +00:00
README Require Linux kernel 3.2 or later on x86 / x86_64. 2017-05-08 10:45:20 +00:00
README.pretty-printers Fix mutex pretty printer test and pretty printer output. 2017-01-20 14:56:39 +01:00
README.tunables tunables: Add support for tunables of uint64_t type 2017-05-17 13:11:55 +05:30
Rules Suppress internal declarations for most of the testsuite. 2017-05-11 19:27:59 -04:00
shlib-versions This is update for configure, build and install of vector math library. 2015-05-14 18:07:06 +03:00
test-skeleton.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
version.h Open master for development 2017-02-05 21:27:52 +05:30
WUR-REPORT * posix/unistd.h (setuid, setreuid, seteuid, setresuid): 2012-08-01 18:12:58 +02:00

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