diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2017-01-12 19:07:54 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2017-01-16 13:25:18 +0000 |
| commit | fbcc3e5004f01653b2885965c59cade25e286c18 (patch) | |
| tree | ccdd40452c6ddce192c33a68832726fde7ee51f9 /util/qemu-thread-posix.c | |
| parent | d7c99a1282ca2de1c344b8aa91be5364e9c6aa8f (diff) | |
qemu-thread: optimize QemuLockCnt with futexes on Linux
This is complex, but I think it is reasonably documented in the source.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170112180800.21085-5-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'util/qemu-thread-posix.c')
| -rw-r--r-- | util/qemu-thread-posix.c | 35 |
1 files changed, 6 insertions, 29 deletions
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c index d20cddec0c..37cd8ba3fe 100644 --- a/util/qemu-thread-posix.c +++ b/util/qemu-thread-posix.c @@ -11,10 +11,6 @@ * */ #include "qemu/osdep.h" -#ifdef __linux__ -#include <sys/syscall.h> -#include <linux/futex.h> -#endif #include "qemu/thread.h" #include "qemu/atomic.h" #include "qemu/notify.h" @@ -294,28 +290,9 @@ void qemu_sem_wait(QemuSemaphore *sem) } #ifdef __linux__ -#define futex(...) syscall(__NR_futex, __VA_ARGS__) - -static inline void futex_wake(QemuEvent *ev, int n) -{ - futex(ev, FUTEX_WAKE, n, NULL, NULL, 0); -} - -static inline void futex_wait(QemuEvent *ev, unsigned val) -{ - while (futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0)) { - switch (errno) { - case EWOULDBLOCK: - return; - case EINTR: - break; /* get out of switch and retry */ - default: - abort(); - } - } -} +#include "qemu/futex.h" #else -static inline void futex_wake(QemuEvent *ev, int n) +static inline void qemu_futex_wake(QemuEvent *ev, int n) { pthread_mutex_lock(&ev->lock); if (n == 1) { @@ -326,7 +303,7 @@ static inline void futex_wake(QemuEvent *ev, int n) pthread_mutex_unlock(&ev->lock); } -static inline void futex_wait(QemuEvent *ev, unsigned val) +static inline void qemu_futex_wait(QemuEvent *ev, unsigned val) { pthread_mutex_lock(&ev->lock); if (ev->value == val) { @@ -338,7 +315,7 @@ static inline void futex_wait(QemuEvent *ev, unsigned val) /* Valid transitions: * - free->set, when setting the event - * - busy->set, when setting the event, followed by futex_wake + * - busy->set, when setting the event, followed by qemu_futex_wake * - set->free, when resetting the event * - free->busy, when waiting * @@ -381,7 +358,7 @@ void qemu_event_set(QemuEvent *ev) if (atomic_read(&ev->value) != EV_SET) { if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) { /* There were waiters, wake them up. */ - futex_wake(ev, INT_MAX); + qemu_futex_wake(ev, INT_MAX); } } } @@ -419,7 +396,7 @@ void qemu_event_wait(QemuEvent *ev) return; } } - futex_wait(ev, EV_BUSY); + qemu_futex_wait(ev, EV_BUSY); } } |