Commit 3c1fcfe2 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Linus Torvalds
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[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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent cdc39363
......@@ -254,6 +254,16 @@ startup_continue:
oi 3(%r12),0x80 # set IDTE flag
.Lchkidte:
#
# find out if the diag 0x9c is available
#
mvc __LC_PGM_NEW_PSW(8),.Lpcdiag9c-.LPG1(%r13)
stap __LC_CPUID+4 # store cpu address
lh %r1,__LC_CPUID+4
diag %r1,0,0x9c # test diag 0x9c
oi 2(%r12),1 # set diag9c flag
.Lchkdiag9c:
lpsw .Lentry-.LPG1(13) # jump to _stext in primary-space,
# virtual and never return ...
.align 8
......@@ -281,6 +291,7 @@ startup_continue:
.Lpccsp:.long 0x00080000,0x80000000 + .Lchkcsp
.Lpcmvpg:.long 0x00080000,0x80000000 + .Lchkmvpg
.Lpcidte:.long 0x00080000,0x80000000 + .Lchkidte
.Lpcdiag9c:.long 0x00080000,0x80000000 + .Lchkdiag9c
.Lmemsize:.long memory_size
.Lmchunk:.long memory_chunk
.Lmflags:.long machine_flags
......
......@@ -250,6 +250,17 @@ startup_continue:
oi 7(%r12),0x80 # set IDTE flag
0:
#
# find out if the diag 0x9c is available
#
la %r1,0f-.LPG1(%r13) # set program check address
stg %r1,__LC_PGM_NEW_PSW+8
stap __LC_CPUID+4 # store cpu address
lh %r1,__LC_CPUID+4
diag %r1,0,0x9c # test diag 0x9c
oi 6(%r12),1 # set diag9c flag
0:
#
# find out if we have the MVCOS instruction
#
......
......@@ -24,57 +24,76 @@ static int __init spin_retry_setup(char *str)
}
__setup("spin_retry=", spin_retry_setup);
static inline void
_diag44(void)
static inline void _raw_yield(void)
{
#ifdef CONFIG_64BIT
if (MACHINE_HAS_DIAG44)
#endif
asm volatile("diag 0,0,0x44");
}
void
_raw_spin_lock_wait(raw_spinlock_t *lp, unsigned int pc)
static inline void _raw_yield_cpu(int cpu)
{
if (MACHINE_HAS_DIAG9C)
asm volatile("diag %0,0,0x9c"
: : "d" (__cpu_logical_map[cpu]));
else
_raw_yield();
}
void _raw_spin_lock_wait(raw_spinlock_t *lp, unsigned int pc)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
while (1) {
if (count-- <= 0) {
_diag44();
unsigned int owner = lp->owner_cpu;
if (owner != 0)
_raw_yield_cpu(~owner);
count = spin_retry;
}
if (__raw_spin_is_locked(lp))
continue;
if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0) {
lp->owner_pc = pc;
return;
}
}
}
EXPORT_SYMBOL(_raw_spin_lock_wait);
int
_raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc)
int _raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
int count;
while (count-- > 0) {
for (count = spin_retry; count > 0; count--) {
if (__raw_spin_is_locked(lp))
continue;
if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0) {
lp->owner_pc = pc;
return 1;
}
}
return 0;
}
EXPORT_SYMBOL(_raw_spin_trylock_retry);
void
_raw_read_lock_wait(raw_rwlock_t *rw)
void _raw_spin_relax(raw_spinlock_t *lock)
{
unsigned int cpu = lock->owner_cpu;
if (cpu != 0)
_raw_yield_cpu(~cpu);
}
EXPORT_SYMBOL(_raw_spin_relax);
void _raw_read_lock_wait(raw_rwlock_t *rw)
{
unsigned int old;
int count = spin_retry;
while (1) {
if (count-- <= 0) {
_diag44();
_raw_yield();
count = spin_retry;
}
if (!__raw_read_can_lock(rw))
......@@ -86,8 +105,7 @@ _raw_read_lock_wait(raw_rwlock_t *rw)
}
EXPORT_SYMBOL(_raw_read_lock_wait);
int
_raw_read_trylock_retry(raw_rwlock_t *rw)
int _raw_read_trylock_retry(raw_rwlock_t *rw)
{
unsigned int old;
int count = spin_retry;
......@@ -103,14 +121,13 @@ _raw_read_trylock_retry(raw_rwlock_t *rw)
}
EXPORT_SYMBOL(_raw_read_trylock_retry);
void
_raw_write_lock_wait(raw_rwlock_t *rw)
void _raw_write_lock_wait(raw_rwlock_t *rw)
{
int count = spin_retry;
while (1) {
if (count-- <= 0) {
_diag44();
_raw_yield();
count = spin_retry;
}
if (!__raw_write_can_lock(rw))
......@@ -121,8 +138,7 @@ _raw_write_lock_wait(raw_rwlock_t *rw)
}
EXPORT_SYMBOL(_raw_write_lock_wait);
int
_raw_write_trylock_retry(raw_rwlock_t *rw)
int _raw_write_trylock_retry(raw_rwlock_t *rw)
{
int count = spin_retry;
......
......@@ -39,6 +39,7 @@ extern unsigned long machine_flags;
#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)
......
......@@ -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 @@ _raw_compare_and_swap(volatile unsigned int *lock,
* (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);
if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0))
_raw_spin_lock_wait(lp, pc);
int old;
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 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
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()
......
......@@ -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
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