Commit 267bc3d4 authored by Anton Blanchard's avatar Anton Blanchard Committed by Linus Torvalds

[PATCH] ppc64: SPLPAR spinlock optimisation

Currently our spinlocks can call into the hypervisor on dedicated processor
machines.  Doing this may slow our locks down, so avoid it where possible.
Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 546b37a5
...@@ -38,6 +38,10 @@ ...@@ -38,6 +38,10 @@
/* waiting for a spinlock... */ /* waiting for a spinlock... */
#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES) #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
/* We only yield to the hypervisor if we are in shared processor mode */
#define SHARED_PROCESSOR (get_paca()->lppaca.xSharedProc)
void __spin_yield(spinlock_t *lock) void __spin_yield(spinlock_t *lock)
{ {
unsigned int lock_value, holder_cpu, yield_count; unsigned int lock_value, holder_cpu, yield_count;
...@@ -65,6 +69,7 @@ void __spin_yield(spinlock_t *lock) ...@@ -65,6 +69,7 @@ void __spin_yield(spinlock_t *lock)
#else /* SPLPAR || ISERIES */ #else /* SPLPAR || ISERIES */
#define __spin_yield(x) barrier() #define __spin_yield(x) barrier()
#define SHARED_PROCESSOR 0
#endif #endif
/* /*
...@@ -104,6 +109,7 @@ void _raw_spin_lock(spinlock_t *lock) ...@@ -104,6 +109,7 @@ void _raw_spin_lock(spinlock_t *lock)
break; break;
do { do {
HMT_low(); HMT_low();
if (SHARED_PROCESSOR)
__spin_yield(lock); __spin_yield(lock);
} while (likely(lock->lock != 0)); } while (likely(lock->lock != 0));
HMT_medium(); HMT_medium();
...@@ -123,6 +129,7 @@ void _raw_spin_lock_flags(spinlock_t *lock, unsigned long flags) ...@@ -123,6 +129,7 @@ void _raw_spin_lock_flags(spinlock_t *lock, unsigned long flags)
local_irq_restore(flags); local_irq_restore(flags);
do { do {
HMT_low(); HMT_low();
if (SHARED_PROCESSOR)
__spin_yield(lock); __spin_yield(lock);
} while (likely(lock->lock != 0)); } while (likely(lock->lock != 0));
HMT_medium(); HMT_medium();
...@@ -134,8 +141,12 @@ EXPORT_SYMBOL(_raw_spin_lock_flags); ...@@ -134,8 +141,12 @@ EXPORT_SYMBOL(_raw_spin_lock_flags);
void spin_unlock_wait(spinlock_t *lock) void spin_unlock_wait(spinlock_t *lock)
{ {
while (lock->lock) while (lock->lock) {
HMT_low();
if (SHARED_PROCESSOR)
__spin_yield(lock); __spin_yield(lock);
}
HMT_medium();
} }
EXPORT_SYMBOL(spin_unlock_wait); EXPORT_SYMBOL(spin_unlock_wait);
...@@ -213,6 +224,7 @@ void _raw_read_lock(rwlock_t *rw) ...@@ -213,6 +224,7 @@ void _raw_read_lock(rwlock_t *rw)
break; break;
do { do {
HMT_low(); HMT_low();
if (SHARED_PROCESSOR)
__rw_yield(rw); __rw_yield(rw);
} while (likely(rw->lock < 0)); } while (likely(rw->lock < 0));
HMT_medium(); HMT_medium();
...@@ -275,6 +287,7 @@ void _raw_write_lock(rwlock_t *rw) ...@@ -275,6 +287,7 @@ void _raw_write_lock(rwlock_t *rw)
break; break;
do { do {
HMT_low(); HMT_low();
if (SHARED_PROCESSOR)
__rw_yield(rw); __rw_yield(rw);
} while (likely(rw->lock != 0)); } while (likely(rw->lock != 0));
HMT_medium(); HMT_medium();
......
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