[PATCH] x86: Don't use MWAIT on AMD Family 10
It doesn't put the CPU into deeper sleep states, so it's better to use the standard
idle loop to save power. But allow to reenable it anyways for benchmarking.
I also removed the obsolete idle=halt on i386
Cc: andreas.herrmann@amd.com
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/i386/kernel/cpu/amd.c b/arch/i386/kernel/cpu/amd.c
index 2d47db4..197cda6 100644
--- a/arch/i386/kernel/cpu/amd.c
+++ b/arch/i386/kernel/cpu/amd.c
@@ -53,6 +53,8 @@
return 0;
}
+int force_mwait __cpuinitdata;
+
static void __cpuinit init_amd(struct cpuinfo_x86 *c)
{
u32 l, h;
@@ -275,6 +277,9 @@
if (amd_apic_timer_broken())
set_bit(X86_FEATURE_LAPIC_TIMER_BROKEN, c->x86_capability);
+
+ if (c->x86 == 0x10 && !force_mwait)
+ clear_bit(X86_FEATURE_MWAIT, c->x86_capability);
}
static unsigned int __cpuinit amd_size_cache(struct cpuinfo_x86 * c, unsigned int size)