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authorLen Brown <len.brown@intel.com>2011-03-30 23:52:29 -0400
committerLen Brown <len.brown@intel.com>2011-08-03 19:06:36 -0400
commit4bfc8288bc4a64529c5547d17349a2a1f4675507 (patch)
treeb7c89fc03fe4cfad612e15554b2095426415b177 /arch/x86/kernel/acpi
parentd91ee5863b71e8c90eaf6035bff3078a85e2e7b5 (diff)
downloadblackbird-op-linux-4bfc8288bc4a64529c5547d17349a2a1f4675507.tar.gz
blackbird-op-linux-4bfc8288bc4a64529c5547d17349a2a1f4675507.zip
x86 idle: move mwait_idle_with_hints() to where it is used
...and make it static no functional change cc: x86@kernel.org Acked-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'arch/x86/kernel/acpi')
-rw-r--r--arch/x86/kernel/acpi/cstate.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 5812404a0d4c..f50e7fb2a201 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -149,6 +149,29 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
}
EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
+/*
+ * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
+ * which can obviate IPI to trigger checking of need_resched.
+ * We execute MONITOR against need_resched and enter optimized wait state
+ * through MWAIT. Whenever someone changes need_resched, we would be woken
+ * up from MWAIT (without an IPI).
+ *
+ * New with Core Duo processors, MWAIT can take some hints based on CPU
+ * capability.
+ */
+void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
+{
+ if (!need_resched()) {
+ if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
+ clflush((void *)&current_thread_info()->flags);
+
+ __monitor((void *)&current_thread_info()->flags, 0, 0);
+ smp_mb();
+ if (!need_resched())
+ __mwait(ax, cx);
+ }
+}
+
void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
{
unsigned int cpu = smp_processor_id();
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