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[Qemu-devel] [PATCH v2 05/13] include/processor.h: define cpu_relax()
From: |
Emilio G. Cota |
Subject: |
[Qemu-devel] [PATCH v2 05/13] include/processor.h: define cpu_relax() |
Date: |
Thu, 7 Apr 2016 13:32:30 -0400 |
Taken from the linux kernel.
Signed-off-by: Emilio G. Cota <address@hidden>
---
include/qemu/processor.h | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
create mode 100644 include/qemu/processor.h
diff --git a/include/qemu/processor.h b/include/qemu/processor.h
new file mode 100644
index 0000000..675a00a
--- /dev/null
+++ b/include/qemu/processor.h
@@ -0,0 +1,28 @@
+#ifndef QEMU_PROCESSOR_H
+#define QEMU_PROCESSOR_H
+
+#include "qemu/atomic.h"
+
+#if defined(__i386__) || defined(__x86_64__)
+#define cpu_relax() asm volatile("rep; nop" ::: "memory")
+#endif
+
+#ifdef __ia64__
+#define cpu_relax() asm volatile("hint @pause" ::: "memory")
+#endif
+
+#ifdef __aarch64__
+#define cpu_relax() asm volatile("yield" ::: "memory")
+#endif
+
+#if defined(__powerpc64__)
+/* set Hardware Multi-Threading (HMT) priority to low; then back to medium */
+#define cpu_relax() asm volatile("or 1, 1, 1;"
+ "or 2, 2, 2;" ::: "memory")
+#endif
+
+#ifndef cpu_relax
+#define cpu_relax() barrier()
+#endif
+
+#endif /* QEMU_PROCESSOR_H */
--
2.5.0
- [Qemu-devel] [PATCH v2 00/10] tb hash improvements, Emilio G. Cota, 2016/04/07
- [Qemu-devel] [PATCH v2 05/13] include/processor.h: define cpu_relax(),
Emilio G. Cota <=
- [Qemu-devel] [PATCH v2 12/13] qht: add test program, Emilio G. Cota, 2016/04/07
- [Qemu-devel] [PATCH v2 09/13] exec: add tb_hash_func5, derived from xxhash, Emilio G. Cota, 2016/04/07
- [Qemu-devel] [PATCH v2 04/13] seqlock: rename write_lock/unlock to write_begin/end, Emilio G. Cota, 2016/04/07
- [Qemu-devel] [PATCH v2 06/13] qemu-thread: add simple test-and-set spinlock, Emilio G. Cota, 2016/04/07