parisc: Switch to more fine grained lws locks
Increase the number of lws locks to 256 entries (instead of 16) and
choose lock entry based on bits 3-11 (instead of 4-7) of the relevant
address. With this change we archieve more fine-grained locking in
futex syscalls and thus reduce the number of possible stalls.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h
index c459f656..fceb9cf 100644
--- a/arch/parisc/include/asm/futex.h
+++ b/arch/parisc/include/asm/futex.h
@@ -16,7 +16,7 @@ static inline void
_futex_spin_lock_irqsave(u32 __user *uaddr, unsigned long int *flags)
{
extern u32 lws_lock_start[];
- long index = ((long)uaddr & 0xf0) >> 2;
+ long index = ((long)uaddr & 0x3f8) >> 1;
arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
local_irq_save(*flags);
arch_spin_lock(s);
@@ -26,7 +26,7 @@ static inline void
_futex_spin_unlock_irqrestore(u32 __user *uaddr, unsigned long int *flags)
{
extern u32 lws_lock_start[];
- long index = ((long)uaddr & 0xf0) >> 2;
+ long index = ((long)uaddr & 0x3f8) >> 1;
arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
arch_spin_unlock(s);
local_irq_restore(*flags);
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 3ad61a1..3225037 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -571,8 +571,8 @@
ldil L%lws_lock_start, %r20
ldo R%lws_lock_start(%r20), %r28
- /* Extract four bits from r26 and hash lock (Bits 4-7) */
- extru %r26, 27, 4, %r20
+ /* Extract eight bits from r26 and hash lock (Bits 3-11) */
+ extru %r26, 28, 8, %r20
/* Find lock to use, the hash is either one of 0 to
15, multiplied by 16 (keep it 16-byte aligned)
@@ -761,8 +761,8 @@
ldil L%lws_lock_start, %r20
ldo R%lws_lock_start(%r20), %r28
- /* Extract four bits from r26 and hash lock (Bits 4-7) */
- extru %r26, 27, 4, %r20
+ /* Extract eight bits from r26 and hash lock (Bits 3-11) */
+ extru %r26, 28, 8, %r20
/* Find lock to use, the hash is either one of 0 to
15, multiplied by 16 (keep it 16-byte aligned)
@@ -950,7 +950,7 @@
.align L1_CACHE_BYTES
ENTRY(lws_lock_start)
/* lws locks */
- .rept 16
+ .rept 256
/* Keep locks aligned at 16-bytes */
.word 1
.word 0