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| author | Jan Beulich <jbeulich@novell.com> | 2008-09-05 13:27:45 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-09-05 17:06:20 +0200 |
| commit | 74e91604b2452c15bbe72d77b37cf47ed0310d13 (patch) | |
| tree | 4308d55a7b19bdd390805c50e2ce9d283825522a /include/asm-x86 | |
| parent | 08f5fcbe6e0ea029c7e9b1b1c338700ab7809daf (diff) | |
| download | op-kernel-dev-74e91604b2452c15bbe72d77b37cf47ed0310d13.zip op-kernel-dev-74e91604b2452c15bbe72d77b37cf47ed0310d13.tar.gz | |
x86: ticket spin locks: reduce instruction dependencies
Reduce the amount of partial register accesses in the NR_CPUS < 256
case, and slightly weaken resource dependencies in the other case.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-x86')
| -rw-r--r-- | include/asm-x86/spinlock.h | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/include/asm-x86/spinlock.h b/include/asm-x86/spinlock.h index 63d3b61..b5a4551 100644 --- a/include/asm-x86/spinlock.h +++ b/include/asm-x86/spinlock.h @@ -21,8 +21,10 @@ #ifdef CONFIG_X86_32 # define LOCK_PTR_REG "a" +# define REG_PTR_MODE "k" #else # define LOCK_PTR_REG "D" +# define REG_PTR_MODE "q" #endif #if defined(CONFIG_X86_32) && \ @@ -77,19 +79,17 @@ static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock) static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock) { - int tmp; - short new; + int tmp, new; - asm volatile("movw %2,%w0\n\t" + asm volatile("movzwl %2, %0\n\t" "cmpb %h0,%b0\n\t" + "leal 0x100(%" REG_PTR_MODE "0), %1\n\t" "jne 1f\n\t" - "movw %w0,%w1\n\t" - "incb %h1\n\t" LOCK_PREFIX "cmpxchgw %w1,%2\n\t" "1:" "sete %b1\n\t" "movzbl %b1,%0\n\t" - : "=&a" (tmp), "=&Q" (new), "+m" (lock->slock) + : "=&a" (tmp), "=&q" (new), "+m" (lock->slock) : : "memory", "cc"); @@ -136,8 +136,8 @@ static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock) "movl %0,%1\n\t" "roll $16, %0\n\t" "cmpl %0,%1\n\t" + "leal 0x00010000(%" REG_PTR_MODE "0), %1\n\t" "jne 1f\n\t" - "addl $0x00010000, %1\n\t" LOCK_PREFIX "cmpxchgl %1,%2\n\t" "1:" "sete %b1\n\t" |
