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| author | Tony Luck <tony.luck@intel.com> | 2009-10-12 18:51:41 +0200 |
|---|---|---|
| committer | Tony Luck <tony.luck@intel.com> | 2009-10-13 23:28:31 +0200 |
| commit | 1502f08edc040b6ba4b986454416564088995e79 (patch) | |
| tree | c6bc0d0c01d9bbc5503b86db71ca977d1b89e0f1 /arch/ia64 | |
| parent | [IA64] Squeeze ticket locks back into 4 bytes. (diff) | |
| download | linux-1502f08edc040b6ba4b986454416564088995e79.tar.xz linux-1502f08edc040b6ba4b986454416564088995e79.zip | |
[IA64] SMT friendly version of spin_unlock_wait()
We can be kinder to SMT systems in spin_unlock_wait.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64')
| -rw-r--r-- | arch/ia64/include/asm/spinlock.h | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h index 4fa502739d64..239ecdc9516d 100644 --- a/arch/ia64/include/asm/spinlock.h +++ b/arch/ia64/include/asm/spinlock.h @@ -75,6 +75,20 @@ static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock) ACCESS_ONCE(*p) = (tmp + 2) & ~1; } +static __always_inline void __ticket_spin_unlock_wait(raw_spinlock_t *lock) +{ + int *p = (int *)&lock->lock, ticket; + + ia64_invala(); + + for (;;) { + asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory"); + if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK)) + return; + cpu_relax(); + } +} + static inline int __ticket_spin_is_locked(raw_spinlock_t *lock) { long tmp = ACCESS_ONCE(lock->lock); @@ -123,8 +137,7 @@ static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock, static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock) { - while (__raw_spin_is_locked(lock)) - cpu_relax(); + __ticket_spin_unlock_wait(lock); } #define __raw_read_can_lock(rw) (*(volatile int *)(rw) >= 0) |