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Subject[PATCH 3/3] s390: enable ARCH_USE_CMPXCHG_LOCKREF
Date
Enable ARCH_USE_CMPXCHG_LOCKREF for 64 bit 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>
---
arch/s390/Kconfig | 1 +
arch/s390/include/asm/spinlock.h | 5 +++++
2 files changed, 6 insertions(+)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 9789282..6651695 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -93,6 +93,7 @@ config S390
select ARCH_INLINE_WRITE_UNLOCK_IRQ
select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
select ARCH_SAVE_PAGE_KEYS if HIBERNATION
+ select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS2
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 void arch_spin_lock_wait_flags(arch_spinlock_t *, unsigned long flags);
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;
--
1.8.3.4


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