s390: enable ARCH_USE_CMPXCHG_LOCKREF
Enable ARCH_USE_CMPXCHG_LOCKREF since it shows performance improvements
with Linus' simple stat() test case of up to 50% on a 30 cpu system.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h
index 701fe8c..83e5d216 100644
--- a/arch/s390/include/asm/spinlock.h
+++ b/arch/s390/include/asm/spinlock.h
@@ -44,6 +44,11 @@
extern int arch_spin_trylock_retry(arch_spinlock_t *);
extern void arch_spin_relax(arch_spinlock_t *lock);
+static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
+{
+ return lock.owner_cpu == 0;
+}
+
static inline void arch_spin_lock(arch_spinlock_t *lp)
{
int old;