s390/spinlock: add compare-and-delay to lock wait loops

Add the compare-and-delay instruction to the spin-lock and rw-lock
retry loops. A CPU executing the compare-and-delay instruction stops
until the lock value has changed. This is done to make the locking
code for contended locks to behave better in regard to the multi-
hreading facility. A thread of a core executing a compare-and-delay
will allow the other threads of a core to get a larger share of the
core resources.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
上级 55b5eb75
...@@ -57,6 +57,7 @@ extern void detect_memory_memblock(void); ...@@ -57,6 +57,7 @@ extern void detect_memory_memblock(void);
#define MACHINE_FLAG_TE (1UL << 15) #define MACHINE_FLAG_TE (1UL << 15)
#define MACHINE_FLAG_TLB_LC (1UL << 17) #define MACHINE_FLAG_TLB_LC (1UL << 17)
#define MACHINE_FLAG_VX (1UL << 18) #define MACHINE_FLAG_VX (1UL << 18)
#define MACHINE_FLAG_CAD (1UL << 19)
#define MACHINE_IS_VM (S390_lowcore.machine_flags & MACHINE_FLAG_VM) #define MACHINE_IS_VM (S390_lowcore.machine_flags & MACHINE_FLAG_VM)
#define MACHINE_IS_KVM (S390_lowcore.machine_flags & MACHINE_FLAG_KVM) #define MACHINE_IS_KVM (S390_lowcore.machine_flags & MACHINE_FLAG_KVM)
...@@ -80,6 +81,7 @@ extern void detect_memory_memblock(void); ...@@ -80,6 +81,7 @@ extern void detect_memory_memblock(void);
#define MACHINE_HAS_TE (0) #define MACHINE_HAS_TE (0)
#define MACHINE_HAS_TLB_LC (0) #define MACHINE_HAS_TLB_LC (0)
#define MACHINE_HAS_VX (0) #define MACHINE_HAS_VX (0)
#define MACHINE_HAS_CAD (0)
#else /* CONFIG_64BIT */ #else /* CONFIG_64BIT */
#define MACHINE_HAS_IEEE (1) #define MACHINE_HAS_IEEE (1)
#define MACHINE_HAS_CSP (1) #define MACHINE_HAS_CSP (1)
...@@ -93,6 +95,7 @@ extern void detect_memory_memblock(void); ...@@ -93,6 +95,7 @@ extern void detect_memory_memblock(void);
#define MACHINE_HAS_TE (S390_lowcore.machine_flags & MACHINE_FLAG_TE) #define MACHINE_HAS_TE (S390_lowcore.machine_flags & MACHINE_FLAG_TE)
#define MACHINE_HAS_TLB_LC (S390_lowcore.machine_flags & MACHINE_FLAG_TLB_LC) #define MACHINE_HAS_TLB_LC (S390_lowcore.machine_flags & MACHINE_FLAG_TLB_LC)
#define MACHINE_HAS_VX (S390_lowcore.machine_flags & MACHINE_FLAG_VX) #define MACHINE_HAS_VX (S390_lowcore.machine_flags & MACHINE_FLAG_VX)
#define MACHINE_HAS_CAD (S390_lowcore.machine_flags & MACHINE_FLAG_CAD)
#endif /* CONFIG_64BIT */ #endif /* CONFIG_64BIT */
/* /*
......
...@@ -393,9 +393,27 @@ static __init void detect_machine_facilities(void) ...@@ -393,9 +393,27 @@ static __init void detect_machine_facilities(void)
S390_lowcore.machine_flags |= MACHINE_FLAG_TLB_LC; S390_lowcore.machine_flags |= MACHINE_FLAG_TLB_LC;
if (test_facility(129)) if (test_facility(129))
S390_lowcore.machine_flags |= MACHINE_FLAG_VX; S390_lowcore.machine_flags |= MACHINE_FLAG_VX;
if (test_facility(128))
S390_lowcore.machine_flags |= MACHINE_FLAG_CAD;
#endif #endif
} }
static int __init nocad_setup(char *str)
{
S390_lowcore.machine_flags &= ~MACHINE_FLAG_CAD;
return 0;
}
early_param("nocad", nocad_setup);
static int __init cad_init(void)
{
if (MACHINE_HAS_CAD)
/* Enable problem state CAD. */
__ctl_set_bit(2, 3);
return 0;
}
early_initcall(cad_init);
static __init void rescue_initrd(void) static __init void rescue_initrd(void)
{ {
#ifdef CONFIG_BLK_DEV_INITRD #ifdef CONFIG_BLK_DEV_INITRD
......
...@@ -12,7 +12,15 @@ ...@@ -12,7 +12,15 @@
#include <linux/smp.h> #include <linux/smp.h>
#include <asm/io.h> #include <asm/io.h>
int spin_retry = 1000; int spin_retry = -1;
static int __init spin_retry_init(void)
{
if (spin_retry < 0)
spin_retry = MACHINE_HAS_CAD ? 10 : 1000;
return 0;
}
early_initcall(spin_retry_init);
/** /**
* spin_retry= parameter * spin_retry= parameter
...@@ -24,6 +32,11 @@ static int __init spin_retry_setup(char *str) ...@@ -24,6 +32,11 @@ static int __init spin_retry_setup(char *str)
} }
__setup("spin_retry=", spin_retry_setup); __setup("spin_retry=", spin_retry_setup);
static inline void _raw_compare_and_delay(unsigned int *lock, unsigned int old)
{
asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock));
}
void arch_spin_lock_wait(arch_spinlock_t *lp) void arch_spin_lock_wait(arch_spinlock_t *lp)
{ {
unsigned int cpu = SPINLOCK_LOCKVAL; unsigned int cpu = SPINLOCK_LOCKVAL;
...@@ -46,6 +59,8 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) ...@@ -46,6 +59,8 @@ void arch_spin_lock_wait(arch_spinlock_t *lp)
/* Loop for a while on the lock value. */ /* Loop for a while on the lock value. */
count = spin_retry; count = spin_retry;
do { do {
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&lp->lock, owner);
owner = ACCESS_ONCE(lp->lock); owner = ACCESS_ONCE(lp->lock);
} while (owner && count-- > 0); } while (owner && count-- > 0);
if (!owner) if (!owner)
...@@ -84,6 +99,8 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) ...@@ -84,6 +99,8 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
/* Loop for a while on the lock value. */ /* Loop for a while on the lock value. */
count = spin_retry; count = spin_retry;
do { do {
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&lp->lock, owner);
owner = ACCESS_ONCE(lp->lock); owner = ACCESS_ONCE(lp->lock);
} while (owner && count-- > 0); } while (owner && count-- > 0);
if (!owner) if (!owner)
...@@ -100,11 +117,19 @@ EXPORT_SYMBOL(arch_spin_lock_wait_flags); ...@@ -100,11 +117,19 @@ EXPORT_SYMBOL(arch_spin_lock_wait_flags);
int arch_spin_trylock_retry(arch_spinlock_t *lp) int arch_spin_trylock_retry(arch_spinlock_t *lp)
{ {
unsigned int cpu = SPINLOCK_LOCKVAL;
unsigned int owner;
int count; int count;
for (count = spin_retry; count > 0; count--) for (count = spin_retry; count > 0; count--) {
if (arch_spin_trylock_once(lp)) owner = ACCESS_ONCE(lp->lock);
return 1; /* Try to get the lock if it is free. */
if (!owner) {
if (_raw_compare_and_swap(&lp->lock, 0, cpu))
return 1;
} else if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&lp->lock, owner);
}
return 0; return 0;
} }
EXPORT_SYMBOL(arch_spin_trylock_retry); EXPORT_SYMBOL(arch_spin_trylock_retry);
...@@ -126,8 +151,11 @@ void _raw_read_lock_wait(arch_rwlock_t *rw) ...@@ -126,8 +151,11 @@ void _raw_read_lock_wait(arch_rwlock_t *rw)
} }
old = ACCESS_ONCE(rw->lock); old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner); owner = ACCESS_ONCE(rw->owner);
if ((int) old < 0) if ((int) old < 0) {
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&rw->lock, old);
continue; continue;
}
if (_raw_compare_and_swap(&rw->lock, old, old + 1)) if (_raw_compare_and_swap(&rw->lock, old, old + 1))
return; return;
} }
...@@ -141,8 +169,11 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw) ...@@ -141,8 +169,11 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw)
while (count-- > 0) { while (count-- > 0) {
old = ACCESS_ONCE(rw->lock); old = ACCESS_ONCE(rw->lock);
if ((int) old < 0) if ((int) old < 0) {
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&rw->lock, old);
continue; continue;
}
if (_raw_compare_and_swap(&rw->lock, old, old + 1)) if (_raw_compare_and_swap(&rw->lock, old, old + 1))
return 1; return 1;
} }
...@@ -173,6 +204,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev) ...@@ -173,6 +204,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev)
} }
if ((old & 0x7fffffff) == 0 && (int) prev >= 0) if ((old & 0x7fffffff) == 0 && (int) prev >= 0)
break; break;
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&rw->lock, old);
} }
} }
EXPORT_SYMBOL(_raw_write_lock_wait); EXPORT_SYMBOL(_raw_write_lock_wait);
...@@ -201,6 +234,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw) ...@@ -201,6 +234,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw)
smp_rmb(); smp_rmb();
if ((old & 0x7fffffff) == 0 && (int) prev >= 0) if ((old & 0x7fffffff) == 0 && (int) prev >= 0)
break; break;
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&rw->lock, old);
} }
} }
EXPORT_SYMBOL(_raw_write_lock_wait); EXPORT_SYMBOL(_raw_write_lock_wait);
...@@ -214,8 +249,11 @@ int _raw_write_trylock_retry(arch_rwlock_t *rw) ...@@ -214,8 +249,11 @@ int _raw_write_trylock_retry(arch_rwlock_t *rw)
while (count-- > 0) { while (count-- > 0) {
old = ACCESS_ONCE(rw->lock); old = ACCESS_ONCE(rw->lock);
if (old) if (old) {
if (MACHINE_HAS_CAD)
_raw_compare_and_delay(&rw->lock, old);
continue; continue;
}
if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000)) if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
return 1; return 1;
} }
......
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