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[Qemu-devel] [PATCH v6 05/15] qemu-thread: add simple test-and-set spinl
From: |
Emilio G. Cota |
Subject: |
[Qemu-devel] [PATCH v6 05/15] qemu-thread: add simple test-and-set spinlock |
Date: |
Tue, 24 May 2016 21:13:12 -0400 |
From: Guillaume Delbergue <address@hidden>
Signed-off-by: Guillaume Delbergue <address@hidden>
[Rewritten. - Paolo]
Signed-off-by: Paolo Bonzini <address@hidden>
[Emilio's additions: use TAS instead of atomic_xchg; emit acquire/release
barriers; return bool from trylock; call cpu_relax() while spinning;
optimize for uncontended locks by acquiring the lock with TAS instead
of TATAS; add qemu_spin_locked().]
Signed-off-by: Emilio G. Cota <address@hidden>
---
include/qemu/thread.h | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/include/qemu/thread.h b/include/qemu/thread.h
index bdae6df..c5d71cf 100644
--- a/include/qemu/thread.h
+++ b/include/qemu/thread.h
@@ -1,6 +1,8 @@
#ifndef __QEMU_THREAD_H
#define __QEMU_THREAD_H 1
+#include "qemu/processor.h"
+#include "qemu/atomic.h"
typedef struct QemuMutex QemuMutex;
typedef struct QemuCond QemuCond;
@@ -60,4 +62,37 @@ struct Notifier;
void qemu_thread_atexit_add(struct Notifier *notifier);
void qemu_thread_atexit_remove(struct Notifier *notifier);
+typedef struct QemuSpin {
+ int value;
+} QemuSpin;
+
+static inline void qemu_spin_init(QemuSpin *spin)
+{
+ __sync_lock_release(&spin->value);
+}
+
+static inline void qemu_spin_lock(QemuSpin *spin)
+{
+ while (unlikely(__sync_lock_test_and_set(&spin->value, true))) {
+ while (atomic_read(&spin->value)) {
+ cpu_relax();
+ }
+ }
+}
+
+static inline bool qemu_spin_trylock(QemuSpin *spin)
+{
+ return __sync_lock_test_and_set(&spin->value, true);
+}
+
+static inline bool qemu_spin_locked(QemuSpin *spin)
+{
+ return atomic_read(&spin->value);
+}
+
+static inline void qemu_spin_unlock(QemuSpin *spin)
+{
+ __sync_lock_release(&spin->value);
+}
+
#endif
--
2.5.0
- [Qemu-devel] [PATCH v6 00/15] tb hash improvements, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 03/15] seqlock: rename write_lock/unlock to write_begin/end, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 06/15] exec: add tb_hash_func5, derived from xxhash, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 02/15] seqlock: remove optional mutex, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 09/15] qdist: add test program, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 05/15] qemu-thread: add simple test-and-set spinlock,
Emilio G. Cota <=
- [Qemu-devel] [PATCH v6 04/15] include/processor.h: define cpu_relax(), Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 11/15] qht: add test program, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 01/15] compiler.h: add QEMU_ALIGNED() to enforce struct alignment, Emilio G. Cota, 2016/05/24
- [Qemu-devel] [PATCH v6 15/15] translate-all: add tb hash bucket info to 'info jit' dump, Emilio G. Cota, 2016/05/24