diff mbox

[v2,07/13] qemu-thread: call cpu_relax() while spinning

Message ID 1460050358-25025-8-git-send-email-cota@braap.org
State New
Headers show

Commit Message

Emilio Cota April 7, 2016, 5:32 p.m. UTC 
Signed-off-by: Emilio G. Cota <cota@braap.org>
---
 include/qemu/thread.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Richard Henderson April 8, 2016, 6:39 p.m. UTC | #1 
On 04/07/2016 10:32 AM, Emilio G. Cota wrote:
>      do {
> -        while (atomic_read(&spin->value));
> +        while (atomic_read(&spin->value)) {
> +            cpu_relax();
> +        }

Please just merge this with the previous patch.


r~
diff mbox

Patch

diff --git a/include/qemu/thread.h b/include/qemu/thread.h
index 1aa843b..599965e 100644
--- a/include/qemu/thread.h
+++ b/include/qemu/thread.h
@@ -2,6 +2,7 @@ 
 #define __QEMU_THREAD_H 1
 
 #include <errno.h>
+#include "qemu/processor.h"
 #include "qemu/atomic.h"
 
 typedef struct QemuMutex QemuMutex;
@@ -74,7 +75,9 @@  static inline void qemu_spin_init(QemuSpin *spin)
 static inline void qemu_spin_lock(QemuSpin *spin)
 {
     do {
-        while (atomic_read(&spin->value));
+        while (atomic_read(&spin->value)) {
+            cpu_relax();
+        }
     } while (atomic_xchg(&spin->value, true));
 }