Use cpu_relax() in __acpi_acquire_global_lock() etc. This could be considered overkill given the previous unlikely(), but it is busy-looping in case of false condition after all... Tested on 2.6.17-mm1, i386 only (no x86_64 here). Signed-off-by: Andreas Mohr <andi@xxxxxxxx> diff -urN linux-2.6.17-mm1.orig/include/asm-i386/acpi.h linux-2.6.17-mm1.my/include/asm-i386/acpi.h --- linux-2.6.17-mm1.orig/include/asm-i386/acpi.h 2006-06-19 10:57:27.000000000 +0200 +++ linux-2.6.17-mm1.my/include/asm-i386/acpi.h 2006-06-21 14:43:24.000000000 +0200 @@ -61,11 +61,14 @@ __acpi_acquire_global_lock (unsigned int *lock) { unsigned int old, new, val; - do { + while (1) { old = *lock; new = (((old & ~0x3) + 2) + ((old >> 1) & 0x1)); val = cmpxchg(lock, old, new); - } while (unlikely (val != old)); + if (likely(val == old)) + break; + cpu_relax(); + } return (new < 3) ? -1 : 0; } @@ -73,11 +76,14 @@ __acpi_release_global_lock (unsigned int *lock) { unsigned int old, new, val; - do { + while (1) { old = *lock; new = old & ~0x3; val = cmpxchg(lock, old, new); - } while (unlikely (val != old)); + if (likely(val == old)) + break; + cpu_relax(); + } return old & 0x1; } diff -urN linux-2.6.17-mm1.orig/include/asm-x86_64/acpi.h linux-2.6.17-mm1.my/include/asm-x86_64/acpi.h --- linux-2.6.17-mm1.orig/include/asm-x86_64/acpi.h 2006-06-21 14:28:19.000000000 +0200 +++ linux-2.6.17-mm1.my/include/asm-x86_64/acpi.h 2006-06-21 14:43:24.000000000 +0200 @@ -59,11 +59,14 @@ __acpi_acquire_global_lock (unsigned int *lock) { unsigned int old, new, val; - do { + while (1) { old = *lock; new = (((old & ~0x3) + 2) + ((old >> 1) & 0x1)); val = cmpxchg(lock, old, new); - } while (unlikely (val != old)); + if (likely(val == old)) + break; + cpu_relax(); + } return (new < 3) ? -1 : 0; } @@ -75,7 +78,10 @@ old = *lock; new = old & ~0x3; val = cmpxchg(lock, old, new); - } while (unlikely (val != old)); + if (likely(val == old)) + break; + cpu_relax(); + } return old & 0x1; } - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html