@@ -402,6 +402,23 @@ static inline unsigned long __pack_fe01(unsigned int fpmode)
#ifdef CONFIG_PPC64
#define cpu_relax() do { HMT_low(); HMT_medium(); barrier(); } while (0)
+
+#ifndef spin_begin
+#define spin_begin() HMT_low()
+#endif
+
+#ifndef spin_cpu_relax
+#define spin_cpu_relax() barrier()
+#endif
+
+#ifndef spin_cpu_yield
+#define spin_cpu_yield()
+#endif
+
+#ifndef spin_end
+#define spin_end() HMT_medium()
+#endif
+
#else
#define cpu_relax() barrier()
#endif
new file mode 100644
@@ -0,0 +1,48 @@
+/* Misc low level processor primitives */
+#ifndef _LINUX_PROCESSOR_H
+#define _LINUX_PROCESSOR_H
+
+#include <asm/processor.h>
+
+/*
+ * spin_begin is used before beginning a busy-wait loop, and must be paired
+ * with spin_end when the loop is exited. spin_cpu_relax must be called
+ * within the loop.
+ *
+ * These loop body should be as small and fast as possible, on the order of
+ * tens of instructions/cycles as a guide. It should and avoid calling
+ * cpu_relax, or any "spin" or sleep type of primitive including nested uses
+ * of these primitives. It should not lock or take any other resource.
+ * Violations of this will not cause a bug, but may cause sub optimal
+ * performance.
+ *
+ * These loops are optimized to be used where wait times are expected to be
+ * less than the cost of a context switch (and associated overhead).
+ *
+ * Detection of resource owner and decision to spin or sleep or guest-yield
+ * (e.g., spin lock holder vcpu preempted, or mutex owner not on CPU) can be
+ * tested within the busy loop body if necessary.
+ */
+#ifndef spin_begin
+#define spin_begin()
+#endif
+
+#ifndef spin_cpu_relax
+#define spin_cpu_relax() cpu_relax()
+#endif
+
+/*
+ * spin_cpu_yield may be called to yield (undirected) to the hypervisor if
+ * necessary. This should be used if the wait is expected to take longer
+ * than context switch overhead, but we can't sleep or do a directed yield.
+ */
+#ifndef spin_cpu_yield
+#define spin_cpu_yield() cpu_relax_yield()
+#endif
+
+#ifndef spin_end
+#define spin_end()
+#endif
+
+#endif /* _LINUX_PROCESSOR_H */
+
@@ -10,6 +10,7 @@
#include <linux/mm.h>
#include <linux/stackprotector.h>
#include <linux/suspend.h>
+#include <linux/processor.h>
#include <asm/tlb.h>
@@ -63,9 +64,13 @@ static noinline int __cpuidle cpu_idle_poll(void)
trace_cpu_idle_rcuidle(0, smp_processor_id());
local_irq_enable();
stop_critical_timings();
+
+ spin_begin();
while (!tif_need_resched() &&
(cpu_idle_force_poll || tick_check_broadcast_expired()))
- cpu_relax();
+ spin_cpu_relax();
+ spin_end();
+
start_critical_timings();
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
rcu_idle_exit();