[PATCH] Directed yield: direct yield of spinlocks for s390.
Use the new diagnose 0x9c in the spinlock implementation for s390. It
yields the remaining timeslice of the virtual cpu that tries to acquire a
lock to the virtual cpu that is the current holder of the lock.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-s390/setup.h b/include/asm-s390/setup.h
index f195973..5d72eda 100644
--- a/include/asm-s390/setup.h
+++ b/include/asm-s390/setup.h
@@ -39,6 +39,7 @@
#define MACHINE_IS_P390 (machine_flags & 4)
#define MACHINE_HAS_MVPG (machine_flags & 16)
#define MACHINE_HAS_IDTE (machine_flags & 128)
+#define MACHINE_HAS_DIAG9C (machine_flags & 256)
#ifndef __s390x__
#define MACHINE_HAS_IEEE (machine_flags & 2)
diff --git a/include/asm-s390/spinlock.h b/include/asm-s390/spinlock.h
index 5f00fea..6b78af1 100644
--- a/include/asm-s390/spinlock.h
+++ b/include/asm-s390/spinlock.h
@@ -13,6 +13,8 @@
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
+#include <linux/smp.h>
+
static inline int
_raw_compare_and_swap(volatile unsigned int *lock,
unsigned int old, unsigned int new)
@@ -50,34 +52,46 @@
* (the type definitions are in asm/spinlock_types.h)
*/
-#define __raw_spin_is_locked(x) ((x)->lock != 0)
+#define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
#define __raw_spin_unlock_wait(lock) \
- do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
+ do { while (__raw_spin_is_locked(lock)) \
+ _raw_spin_relax(lock); } while (0)
-extern void _raw_spin_lock_wait(raw_spinlock_t *lp, unsigned int pc);
-extern int _raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc);
+extern void _raw_spin_lock_wait(raw_spinlock_t *, unsigned int pc);
+extern int _raw_spin_trylock_retry(raw_spinlock_t *, unsigned int pc);
+extern void _raw_spin_relax(raw_spinlock_t *lock);
static inline void __raw_spin_lock(raw_spinlock_t *lp)
{
unsigned long pc = 1 | (unsigned long) __builtin_return_address(0);
+ int old;
- if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0))
- _raw_spin_lock_wait(lp, pc);
+ old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
+ if (likely(old == 0)) {
+ lp->owner_pc = pc;
+ return;
+ }
+ _raw_spin_lock_wait(lp, pc);
}
static inline int __raw_spin_trylock(raw_spinlock_t *lp)
{
unsigned long pc = 1 | (unsigned long) __builtin_return_address(0);
+ int old;
- if (likely(_raw_compare_and_swap(&lp->lock, 0, pc) == 0))
+ old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
+ if (likely(old == 0)) {
+ lp->owner_pc = pc;
return 1;
+ }
return _raw_spin_trylock_retry(lp, pc);
}
static inline void __raw_spin_unlock(raw_spinlock_t *lp)
{
- _raw_compare_and_swap(&lp->lock, lp->lock, 0);
+ lp->owner_pc = 0;
+ _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0);
}
/*
@@ -154,7 +168,6 @@
return _raw_write_trylock_retry(rw);
}
-#define _raw_spin_relax(lock) cpu_relax()
#define _raw_read_relax(lock) cpu_relax()
#define _raw_write_relax(lock) cpu_relax()
diff --git a/include/asm-s390/spinlock_types.h b/include/asm-s390/spinlock_types.h
index f79a221..b7ac13f 100644
--- a/include/asm-s390/spinlock_types.h
+++ b/include/asm-s390/spinlock_types.h
@@ -6,16 +6,16 @@
#endif
typedef struct {
- volatile unsigned int lock;
+ volatile unsigned int owner_cpu;
+ volatile unsigned int owner_pc;
} __attribute__ ((aligned (4))) raw_spinlock_t;
#define __RAW_SPIN_LOCK_UNLOCKED { 0 }
typedef struct {
volatile unsigned int lock;
- volatile unsigned int owner_pc;
} raw_rwlock_t;
-#define __RAW_RW_LOCK_UNLOCKED { 0, 0 }
+#define __RAW_RW_LOCK_UNLOCKED { 0 }
#endif