This patch adds a default pthreadtypes-arch.h, the idea is to simpify
new ports inclusion and an override is required only if the architecture
adds some arch-specific extensions or requirement.
The default values on the new generic header are based on current
architecture define value and they are not optimal compared to current
code requirements as below.
- On 64 bits __SIZEOF_PTHREAD_BARRIER_T is defined as 32 while is
sizeof (struct pthread_barrier) is 20 bytes.
- On 32 bits __SIZEOF_PTHREAD_ATTR_T is defined as 36 while
sizeof (struct pthread_attr) is 32.
The default values are not changed so the generic header could be
used by some architectures.
Checked with a build on affected abis.
Change-Id: Ie0cd586258a2650f715c1af0c9fe4e7063b0409a
This patch adds a new generic __pthread_rwlock_arch_t definition meant
to be used by new ports. Its layout mimics the current usage on some
64 bits ports and it allows some ports to use the generic definition.
The arch __pthread_rwlock_arch_t definition is moved from
pthreadtypes-arch.h to another arch-specific header (struct_rwlock.h).
Also the static intialization macro for pthread_rwlock_t is set to use
an arch defined on (__PTHREAD_RWLOCK_INITIALIZER) which simplifies its
implementation.
The default pthread_rwlock_t layout differs from current ports with:
1. Internal layout is the same for 32 bits and 64 bits.
2. Internal flag is an unsigned short so it should not required
additional padding to align for word boundary (if it is the case
for the ABI).
Checked with a build on affected abis.
Change-Id: I776a6a986c23199929d28a3dcd30272db21cd1d0
The current way of defining the common mutex definition for POSIX and
C11 on pthreadtypes-arch.h (added by commit 06be6368da) is
not really the best options for newer ports. It requires define some
misleading flags that should be always defined as 0
(__PTHREAD_COMPAT_PADDING_MID and __PTHREAD_COMPAT_PADDING_END), it
exposes options used solely for linuxthreads compat mode
(__PTHREAD_MUTEX_USE_UNION and __PTHREAD_MUTEX_NUSERS_AFTER_KIND), and
requires newer ports to explicit define them (adding more boilerplate
code).
This patch adds a new default __pthread_mutex_s definition meant to
be used by newer ports. Its layout mimics the current usage on both
32 and 64 bits ports and it allows most ports to use the generic
definition. Only ports that use some arch-specific definition (such
as hardware lock-elision or linuxthreads compat) requires specific
headers.
For 32 bit, the generic definitions mimic the other 32-bit ports
of using an union to define the fields uses on adaptive and robust
mutexes (thus not allowing both usage at same time) and by using a
single linked-list for robust mutexes. Both decisions seemed to
follow what recent ports have done and make the resulting
pthread_mutex_t/mtx_t object smaller.
Also the static intialization macro for pthread_mutex_t is set to use
a macro __PTHREAD_MUTEX_INITIALIZER where the architecture can redefine
in its struct_mutex.h if it requires additional fields to be
initialized.
Checked with a build on affected abis.
Change-Id: I30a22c3e3497805fd6e52994c5925897cffcfe13
The new rwlock implementation added by cc25c8b4c1 (2.25) removed
support for lock-elision. This patch removes remaining the
arch-specific unused definitions.
Checked with a build against all affected ABIs.
Change-Id: I5dec8af50e3cd56d7351c52ceff4aa3771b53cd6
This patch adds several new tunables to control the behavior of
elision on supported platforms[1]. Since elision now depends
on tunables, we should always *compile* with elision enabled,
and leave the code disabled, but available for runtime
selection. This gives us *much* better compile-time testing of
the existing code to avoid bit-rot[2].
Tested on ppc, ppc64, ppc64le, s390x and x86_64.
[1] This part of the patch was initially proposed by
Paul Murphy but was "staled" because the framework have changed
since the patch was originally proposed:
https://patchwork.sourceware.org/patch/10342/
[2] This part of the patch was inititally proposed as a RFC by
Carlos O'Donnell. Make sense to me integrate this on the patch:
https://sourceware.org/ml/libc-alpha/2017-05/msg00335.html
* elf/dl-tunables.list: Add elision parameters.
* manual/tunables.texi: Add entries about elision tunable.
* sysdeps/unix/sysv/linux/powerpc/elision-conf.c:
Add callback functions to dynamically enable/disable elision.
Add multiple callbacks functions to set elision parameters.
Deleted __libc_enable_secure check.
* sysdeps/unix/sysv/linux/s390/elision-conf.c: Likewise.
* sysdeps/unix/sysv/linux/x86/elision-conf.c: Likewise.
* configure: Regenerated.
* configure.ac: Option enable_lock_elision was deleted.
* config.h.in: ENABLE_LOCK_ELISION flag was deleted.
* config.make.in: Remove references to enable_lock_elision.
* manual/install.texi: Elision configure option was removed.
* INSTALL: Regenerated to remove enable_lock_elision.
* nptl/Makefile:
Disable elision so it can verify error case for destroying a mutex.
* sysdeps/powerpc/nptl/elide.h:
Cleanup ENABLE_LOCK_ELISION check.
Deleted macros for the case when ENABLE_LOCK_ELISION was not defined.
* sysdeps/s390/configure: Regenerated.
* sysdeps/s390/configure.ac: Remove references to enable_lock_elision..
* nptl/tst-mutex8.c:
Deleted all #ifndef ENABLE_LOCK_ELISION from the test.
* sysdeps/powerpc/powerpc32/sysdep.h:
Deleted all ENABLE_LOCK_ELISION checks.
* sysdeps/powerpc/powerpc64/sysdep.h: Likewise.
* sysdeps/powerpc/sysdep.h: Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/force-elision.h: Likewise.
* sysdeps/unix/sysv/linux/s390/elision-conf.h: Likewise.
* sysdeps/unix/sysv/linux/s390/force-elision.h: Likewise.
* sysdeps/unix/sysv/linux/s390/lowlevellock.h: Likewise.
* sysdeps/unix/sysv/linux/s390/Makefile: Remove references to
enable-lock-elision.
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
This patch adds two new internal defines to set the internal
pthread_mutex_t layout required by the supported ABIS:
1. __PTHREAD_MUTEX_NUSERS_AFTER_KIND which control whether to define
__nusers fields before or after __kind. The preferred value for
is 0 for new ports and it sets __nusers before __kind.
2. __PTHREAD_MUTEX_USE_UNION which control whether internal __spins and
__list members will be place inside an union for linuxthreads
compatibility. The preferred value is 0 for ports and it sets
to not use an union to define both fields.
It fixes the wrong offsets value for __kind value on x86_64-linux-gnu-x32.
Checked with a make check run-built-tests=no on all afected ABIs.
[BZ #22298]
* nptl/allocatestack.c (allocate_stack): Check if
__PTHREAD_MUTEX_HAVE_PREV is non-zero, instead if
__PTHREAD_MUTEX_HAVE_PREV is defined.
* nptl/descr.h (pthread): Likewise.
* nptl/nptl-init.c (__pthread_initialize_minimal_internal):
Likewise.
* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* sysdeps/nptl/pthread.h (PTHREAD_MUTEX_INITIALIZER): Likewise.
* sysdeps/nptl/bits/thread-shared-types.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION): New
defines.
(__pthread_internal_list): Check __PTHREAD_MUTEX_USE_UNION instead
of __WORDSIZE for internal layout.
(__pthread_mutex_s): Check __PTHREAD_MUTEX_NUSERS_AFTER_KIND instead
of __WORDSIZE for internal __nusers layout and __PTHREAD_MUTEX_USE_UNION
instead of __WORDSIZE whether to use an union for __spins and __list
fields.
(__PTHREAD_MUTEX_HAVE_PREV): Define also for __PTHREAD_MUTEX_USE_UNION
case.
* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION): New
defines.
* sysdeps/alpha/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This patch removes all the replicated pthread definition accross the
architectures and consolidates it on shared headers. The new
organization is as follow:
* Architecture specific definition (such as pthread types sizes) are
place in the new pthreadtypes-arch.h header in arch specific path.
* All shared structure definition are moved to a common NPTL header
at sysdeps/nptl/bits/pthreadtypes.h (with now includes the arch
specific one for internal definitions).
* Also, for C11 future thread support, both mutex and condition
definition are placed in a common header at
sysdeps/nptl/bits/thread-shared-types.h.
It is also a refactor patch without expected functional changes.
Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu,
arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu,
m68k-linux-gnu, microblaze-linux-gnu, mips{64}-linux-gnu, nios2-linux-gnu,
powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu,
tile{pro,gx}-linux-gnu, and x86_64-linux-gnu).
* posix/Makefile (headers): Add pthreadtypes-arch.h and
thread-shared-types.h.
* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h: New file: arch
specific thread definition.
* sysdeps/alpha/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/nptl/bits/thread-shared-types.h: New file: shared
thread definition between POSIX and C11.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h.: Remove file.
* sysdeps/alpha/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/nptl/bits/pthreadtypes.h: New file: common thread
definitions shared across all architectures.
This is a new implementation for condition variables, required
after http://austingroupbugs.net/view.php?id=609 to fix bug 13165. In
essence, we need to be stricter in which waiters a signal or broadcast
is required to wake up; this couldn't be solved using the old algorithm.
ISO C++ made a similar clarification, so this also fixes a bug in
current libstdc++, for example.
We can't use the old algorithm anymore because futexes do not guarantee
to wake in FIFO order. Thus, when we wake, we can't simply let any
waiter grab a signal, but we need to ensure that one of the waiters
happening before the signal is woken up. This is something the previous
algorithm violated (see bug 13165).
There's another issue specific to condvars: ABA issues on the underlying
futexes. Unlike mutexes that have just three states, or semaphores that
have no tokens or a limited number of them, the state of a condvar is
the *order* of the waiters. A waiter on a semaphore can grab a token
whenever one is available; a condvar waiter must only consume a signal
if it is eligible to do so as determined by the relative order of the
waiter and the signal.
Therefore, this new algorithm maintains two groups of waiters: Those
eligible to consume signals (G1), and those that have to wait until
previous waiters have consumed signals (G2). Once G1 is empty, G2
becomes the new G1. 64b counters are used to avoid ABA issues.
This condvar doesn't yet use a requeue optimization (ie, on a broadcast,
waking just one thread and requeueing all others on the futex of the
mutex supplied by the program). I don't think doing the requeue is
necessarily the right approach (but I haven't done real measurements
yet):
* If a program expects to wake many threads at the same time and make
that scalable, a condvar isn't great anyway because of how it requires
waiters to operate mutually exclusive (due to the mutex usage). Thus, a
thundering herd problem is a scalability problem with or without the
optimization. Using something like a semaphore might be more
appropriate in such a case.
* The scalability problem is actually at the mutex side; the condvar
could help (and it tries to with the requeue optimization), but it
should be the mutex who decides how that is done, and whether it is done
at all.
* Forcing all but one waiter into the kernel-side wait queue of the
mutex prevents/avoids the use of lock elision on the mutex. Thus, it
prevents the only cure against the underlying scalability problem
inherent to condvars.
* If condvars use short critical sections (ie, hold the mutex just to
check a binary flag or such), which they should do ideally, then forcing
all those waiter to proceed serially with kernel-based hand-off (ie,
futex ops in the mutex' contended state, via the futex wait queues) will
be less efficient than just letting a scalable mutex implementation take
care of it. Our current mutex impl doesn't employ spinning at all, but
if critical sections are short, spinning can be much better.
* Doing the requeue stuff requires all waiters to always drive the mutex
into the contended state. This leads to each waiter having to call
futex_wake after lock release, even if this wouldn't be necessary.
[BZ #13165]
* nptl/pthread_cond_broadcast.c (__pthread_cond_broadcast): Rewrite to
use new algorithm.
* nptl/pthread_cond_destroy.c (__pthread_cond_destroy): Likewise.
* nptl/pthread_cond_init.c (__pthread_cond_init): Likewise.
* nptl/pthread_cond_signal.c (__pthread_cond_signal): Likewise.
* nptl/pthread_cond_wait.c (__pthread_cond_wait): Likewise.
(__pthread_cond_timedwait): Move here from pthread_cond_timedwait.c.
(__condvar_confirm_wakeup, __condvar_cancel_waiting,
__condvar_cleanup_waiting, __condvar_dec_grefs,
__pthread_cond_wait_common): New.
(__condvar_cleanup): Remove.
* npt/pthread_condattr_getclock.c (pthread_condattr_getclock): Adapt.
* npt/pthread_condattr_setclock.c (pthread_condattr_setclock):
Likewise.
* npt/pthread_condattr_getpshared.c (pthread_condattr_getpshared):
Likewise.
* npt/pthread_condattr_init.c (pthread_condattr_init): Likewise.
* nptl/tst-cond1.c: Add comment.
* nptl/tst-cond20.c (do_test): Adapt.
* nptl/tst-cond22.c (do_test): Likewise.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_cond_t): Adapt
structure.
* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/x86/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nptl/internaltypes.h (COND_NWAITERS_SHIFT): Remove.
(COND_CLOCK_BITS): Adapt.
* sysdeps/nptl/pthread.h (PTHREAD_COND_INITIALIZER): Adapt.
* nptl/pthreadP.h (__PTHREAD_COND_CLOCK_MONOTONIC_MASK,
__PTHREAD_COND_SHARED_MASK): New.
* nptl/nptl-printers.py (CLOCK_IDS): Remove.
(ConditionVariablePrinter, ConditionVariableAttributesPrinter): Adapt.
* nptl/nptl_lock_constants.pysym: Adapt.
* nptl/test-cond-printers.py: Adapt.
* sysdeps/unix/sysv/linux/hppa/internaltypes.h (cond_compat_clear,
cond_compat_check_and_clear): Adapt.
* sysdeps/unix/sysv/linux/hppa/pthread_cond_timedwait.c: Remove file ...
* sysdeps/unix/sysv/linux/hppa/pthread_cond_wait.c
(__pthread_cond_timedwait): ... and move here.
* nptl/DESIGN-condvar.txt: Remove file.
* nptl/lowlevelcond.sym: Likewise.
* nptl/pthread_cond_timedwait.c: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: Likewise.
