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2a673dcf |
| 25-May-2023 |
riastradh <riastradh@NetBSD.org> |
libpthread: New pthread__smt_wait to put CPU in low power for spin.
This is now distinct from pthread__smt_pause, which is for spin lock backoff with no paired wakeup.
On Arm, there is a single-bit
libpthread: New pthread__smt_wait to put CPU in low power for spin.
This is now distinct from pthread__smt_pause, which is for spin lock backoff with no paired wakeup.
On Arm, there is a single-bit event register per CPU, and there are two instructions to manage it:
- wfe, wait for event -- if event register is clear, enter low power mode and wait until event register is set; then exit low power mode and clear event register
- sev, signal event -- sets event register on all CPUs (other circumstances like interrupts also set the event register and cause wfe to wake)
These can be used to reduce the power consumption of spinning for a lock, but only if they are actually paired -- if there's no sev, wfe might hang indefinitely. Currently only pthread_spin(3) actually pairs them; the other lock primitives (internal lock, mutex, rwlock) do not -- they have spin lock backoff loops, but no corresponding wakeup to cancel a wfe.
It may be worthwhile to teach the other lock primitives to pair wfe/sev, but that requires some performance measurement to verify it's actually worthwhile. So for now, we just make sure not to use wfe when there's no sev, and keep everything else the same -- this should fix severe performance degredation in libpthread on Arm without hurting anything else.
No change in the generated code on amd64 and i386. No change in the generated code for pthread_spin.c on arm and aarch64 -- changes only the generated code for pthread_lock.c, pthread_mutex.c, and pthread_rwlock.c, as intended.
PR port-arm/57437
XXX pullup-10
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d2be1428 |
| 02-Mar-2012 |
joerg <joerg@NetBSD.org> |
Avoid getcontext() as it triggers clobbering warnings. Use inline assembler to get the fields directly. Saves a system call as side effect.
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1631a780 |
| 24-Feb-2011 |
joerg <joerg@NetBSD.org> |
Allow storing and receiving the LWP private pointer via ucontext_t on all platforms except VAX and IA64. Add fast access via register for AMD64, i386 and SH3 ports. Use this fast access in libpthread
Allow storing and receiving the LWP private pointer via ucontext_t on all platforms except VAX and IA64. Add fast access via register for AMD64, i386 and SH3 ports. Use this fast access in libpthread to replace the stack based pthread_self(). Implement skeleton support for Alpha, HPPA, PowerPC, SPARC and SPARC64, but leave it disabled.
Ports that support this feature provide __HAVE____LWP_GETPRIVATE_FAST in machine/types.h and a corresponding __lwp_getprivate_fast in machine/mcontext.h.
This material is based upon work partially supported by The NetBSD Foundation under a contract with Joerg Sonnenberger.
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c5d359be |
| 25-Jan-2011 |
christos <christos@NetBSD.org> |
make pthread__sp unsigned long.
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a61915e9 |
| 16-May-2009 |
ad <ad@NetBSD.org> |
Remove unused code that's confusing when using cscope/opengrok.
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5c670ea6 |
| 29-Mar-2009 |
ad <ad@NetBSD.org> |
- Make the threadreg code use _lwp_setprivate() instead of MD hooks.
XXX This must not be enabled by default because the LWP private mechanism is reserved for TLS. It is provided only as a test/
- Make the threadreg code use _lwp_setprivate() instead of MD hooks.
XXX This must not be enabled by default because the LWP private mechanism is reserved for TLS. It is provided only as a test/demo.
XXX Since ucontext_t does not contain the thread private variable, for a short time after threads are created their thread specific data is unset. If a signal arrives during that time we are screwed.
- No longer need pthread__osrev.
- Rearrange _lwp_ctl() calls slightly.
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3e1711d6 |
| 23-Jun-2008 |
ad <ad@NetBSD.org> |
pthread__threadreg_get: mark it const.
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ce099b40 |
| 28-Apr-2008 |
martin <martin@NetBSD.org> |
Remove clause 3 and 4 from TNF licenses
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ecdd2c29 |
| 22-Mar-2008 |
ad <ad@NetBSD.org> |
Cheat and add inlines for _atomic_cas_ptr() to work around gcc emitting unneeded PIC stuff in mutex_lock() and mutex_unlock(), when a thread register is used.
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a67e1e34 |
| 10-Feb-2008 |
ad <ad@NetBSD.org> |
- Remove libpthread's atomic ops. - Remove the old spinlock-based mutex and rwlock implementations. - Use the atomic ops from libc.
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66ac2ffa |
| 13-Nov-2007 |
ad <ad@NetBSD.org> |
Mutexes:
- Play scrooge again and chop more cycles off acquire/release. - Spin while the lock holder is running on another CPU (adaptive mutexes). - Do non-atomic release.
Threadreg:
- Add the nec
Mutexes:
- Play scrooge again and chop more cycles off acquire/release. - Spin while the lock holder is running on another CPU (adaptive mutexes). - Do non-atomic release.
Threadreg:
- Add the necessary hooks to use a thread register. - Add the code for i386, using %gs. - Leave i386 code disabled until xen and COMPAT_NETBSD32 have the changes.
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d32ed989 |
| 24-Sep-2007 |
skrll <skrll@NetBSD.org> |
Resurrect the function pointers for lock operations and allow each architecture to provide asm versions of the RAS operations.
We do this because relying on the compiler to get the RAS right is not
Resurrect the function pointers for lock operations and allow each architecture to provide asm versions of the RAS operations.
We do this because relying on the compiler to get the RAS right is not sensible. (It gets alpha wrong and hppa is suboptimal)
Provide asm RAS ops for hppa.
(A slightly different version) reviewed by Andrew Doran.
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f4fd6b79 |
| 08-Sep-2007 |
ad <ad@NetBSD.org> |
- Get rid of self->pt_mutexhint and use pthread__mutex_owned() instead. - Update some comments and fix minor bugs. Minor cosmetic changes. - Replace some spinlocks with mutexes and rwlocks. - Change
- Get rid of self->pt_mutexhint and use pthread__mutex_owned() instead. - Update some comments and fix minor bugs. Minor cosmetic changes. - Replace some spinlocks with mutexes and rwlocks. - Change the process private semaphores to use mutexes and condition variables instead of doing the synchronization directly. Spinlocks are no longer used by the semaphore code.
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a6ed47a5 |
| 07-Sep-2007 |
ad <ad@NetBSD.org> |
Add: pthread__atomic_cas_ptr, pthread__atomic_swap_ptr, pthread__membar_full This is a stopgap until the thorpej-atomic branch is complete.
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562d0d89 |
| 29-Mar-2006 |
cube <cube@NetBSD.org> |
Instead of using hard-coded values for various registers, get them from the current context. Valid values can change depending on how the kernel is setup. i386 and amd64 happen to be setup differen
Instead of using hard-coded values for various registers, get them from the current context. Valid values can change depending on how the kernel is setup. i386 and amd64 happen to be setup differently.
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4e11af46 |
| 24-Dec-2005 |
perry <perry@NetBSD.org> |
Remove leading __ from __(const|inline|signed|volatile) -- it is obsolete.
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94fc83a6 |
| 11-Feb-2004 |
nathanw <nathanw@NetBSD.org> |
Add ucontext conversion macros for an "extra" register set.
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54ba9fed |
| 18-Jan-2003 |
christos <christos@NetBSD.org> |
delint
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9631ace5 |
| 18-Jan-2003 |
christos <christos@NetBSD.org> |
de-lint
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c62a74e6 |
| 18-Jan-2003 |
thorpej <thorpej@NetBSD.org> |
Merge the nathanw_sa branch.
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