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* thread-posix: implement Semaphore with QemuCond and QemuMutexLongpeng(Mike)2022-04-061-3/+2Star
| | | | | | | | | | Now that QemuSemaphore is implemented through pthread_cond_t only, we can use QemuCond and QemuMutex to make the code smaller. Features such as mutex tracing and CLOCK_MONOTONIC timedwait are supported in qemu-sem naturally. Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> Message-Id: <20220222090507.2028-4-longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* thread-posix: remove the posix semaphore supportLongpeng(Mike)2022-04-061-4/+0Star
| | | | | | | | | | | | | | | | | | POSIX specifies an absolute time for sem_timedwait(), it would be affected if the system time is changing, but there is not a relative time or monotonic clock version of sem_timedwait, so we cannot gain from POSIX semaphore any more. An alternative way is to use sem_trywait + usleep, maybe we can remove CONFIG_SEM_TIMEDWAIT in this way? No, because some systems (e.g. mac os) mark the sem_xxx API as deprecated. So maybe remove the usage of POSIX semaphore and turn to use the pthread variant for all systems looks better. Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> Message-Id: <20220222090507.2028-2-longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* util: Use unique type for QemuRecMutex in thread-posix.hRichard Henderson2021-06-161-2/+8
| | | | | | | | | | | We will shortly convert lockable.h to _Generic, and we cannot have two compatible types in the same expansion. Wrap QemuMutex in a struct, and unwrap in qemu-thread-posix.c. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Message-Id: <20210614233143.1221879-6-richard.henderson@linaro.org>
* util: Use real functions for thread-posix QemuRecMutexRichard Henderson2021-06-161-4/+0Star
| | | | | | | | | | | Move the declarations from thread-win32.h into thread.h and remove the macro redirection from thread-posix.h. This will be required by following cleanups. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Message-Id: <20210614233143.1221879-4-richard.henderson@linaro.org>
* qsp: QEMU's Synchronization ProfilerEmilio G. Cota2018-08-231-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The goal of this module is to profile synchronization primitives (i.e. mutexes, recursive mutexes and condition variables) so that scalability issues can be quickly diagnosed. Sync primitives are profiled by QSP based on the vaddr of the object accessed as well as the call site (file:line_nr). That means the same object called from two different call sites will be tracked in separate entries, which might be reported together or separately (see subsequent commit on call site coalescing). Some perf numbers: Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz Command: taskset -c 0 tests/atomic_add-bench -d 5 -m - Before: 54.80 Mops/s - After: 54.75 Mops/s That is, a negligible slowdown due to the now indirect call to qemu_mutex_lock. Note that using a branch instead of an indirect call introduces a more severe slowdown (53.65 Mops/s, i.e. 2% slowdown). Enabling the profiler (with -p, added in this series) is more interesting: - No profiling: 54.75 Mops/s - W/ profiling: 12.53 Mops/s That is, a 4.36X slowdown. We can break down this slowdown by removing the get_clock calls or the entry lookup: - No profiling: 54.75 Mops/s - W/o get_clock: 25.37 Mops/s - W/o entry lookup: 19.30 Mops/s - W/ profiling: 12.53 Mops/s Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* QemuMutex: support --enable-debug-mutexPaolo Bonzini2018-06-281-0/+4
| | | | | | | | | | | | | | We have had some tracing tools for mutex but it's not easy to use them for e.g. dead locks. Let's provide "--enable-debug-mutex" parameter when configure to allow QemuMutex to store the last owner that took specific lock. It will be easy to use this tool to debug deadlocks since we can directly know who took the lock then as long as we can have a debugger attached to the process. Reviewed-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180425025459.5258-4-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* thread-posix: fix qemu_rec_mutex_trylock macroEmilio G. Cota2017-11-141-1/+1
| | | | | | | | We never noticed because it has no users. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <1510273811-13419-1-git-send-email-cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAITPeter Maydell2017-09-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | In qemu-thread-posix.c we have two implementations of the various qemu_sem_* functions, one of which uses native POSIX sem_* and the other of which emulates them with pthread conditions. This is necessary because not all our host OSes support sem_timedwait(). Instead of a hard-coded list of OSes which don't implement sem_timedwait(), which gets out of date, make configure test for the presence of the function and set a new CONFIG_HAVE_SEM_TIMEDWAIT appropriately. In particular, newer NetBSDs have sem_timedwait(), so this commit will switch them over to using it. OSX still does not have an implementation. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Kamil Rytarowski <n54@gmx.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
* qemu-thread: Assert locks are initialized before usingFam Zheng2017-07-041-0/+4
| | | | | | | | | | | | Not all platforms check whether a lock is initialized before used. In particular Linux seems to be more permissive than OSX. Check initialization state explicitly in our code to catch such bugs earlier. Signed-off-by: Fam Zheng <famz@redhat.com> Message-Id: <20170704122325.25634-1-famz@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* qemu-thread: introduce QemuRecMutexPaolo Bonzini2016-10-281-0/+6
| | | | | | | | | | | | GRecMutex is new in glib 2.32, so we cannot use it. Introduce a recursive mutex in qemu-thread instead, which will be used instead of RFifoLock. Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <1477565348-5458-20-git-send-email-pbonzini@redhat.com> Signed-off-by: Fam Zheng <famz@redhat.com>
* Clean up ill-advised or unusual header guardsMarkus Armbruster2016-07-121-2/+2
| | | | | | | Cleaned up with scripts/clean-header-guards.pl. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net>
* Use #include "..." for our own headers, <...> for othersMarkus Armbruster2016-07-121-1/+2
| | | | | | | | | | | | Tracked down with an ugly, brittle and probably buggy Perl script. Also move includes converted to <...> up so they get included before ours where that's obviously okay. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Tested-by: Eric Blake <eblake@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net>
* qemu-thread: add QemuEventPaolo Bonzini2013-10-171-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This emulates Win32 manual-reset events using futexes or conditional variables. Typical ways to use them are with multi-producer, single-consumer data structures, to test for a complex condition whose elements come from different threads: for (;;) { qemu_event_reset(ev); ... test complex condition ... if (condition is true) { break; } qemu_event_wait(ev); } Or more efficiently (but with some duplication): ... evaluate condition ... while (!condition) { qemu_event_reset(ev); ... evaluate condition ... if (!condition) { qemu_event_wait(ev); ... evaluate condition ... } } QemuEvent provides a very fast userspace path in the common case when no other thread is waiting, or the event is not changing state. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* semaphore: fix a hangup problem under load on NetBSD hosts.Izumi Tsutsui2013-08-051-1/+1
| | | | | | | | | | | | | | | | | | | | Fix following bugs in "fallback implementation of counting semaphores with mutex+condvar" added in c166cb72f1676855816340666c3b618beef4b976: - waiting threads are not restarted properly if more than one threads are waiting unblock signals in qemu_sem_timedwait() - possible missing pthread_cond_signal(3) calls when waiting threads are returned by ETIMEDOUT - fix an uninitialized variable The problem is analyzed by and fix is provided by Noriyuki Soda. Also put additional cleanup suggested by Laszlo Ersek: - make QemuSemaphore.count unsigned (it won't be negative) - check a return value of in pthread_cond_wait() in qemu_sem_wait() Signed-off-by: Izumi Tsutsui <tsutsui@ceres.dti.ne.jp> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Message-id: 1372841894-10634-1-git-send-email-tsutsui@ceres.dti.ne.jp Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
* Disable semaphores fallback code for OpenBSDBrad Smith2012-12-281-1/+1
| | | | | | | | Disable the semaphores fallback code for OpenBSD as modern OpenBSD releases now have sem_timedwait(). Signed-off-by: Brad Smith <brad@comstyle.com> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
* misc: move include files to include/qemu/Paolo Bonzini2012-12-191-0/+28
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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