perf counters: protect them against CSTATE transitions
Impact: fix rare lost events problem
There are CPUs whose performance counters misbehave on CSTATE transitions,
so provide a way to just disable/enable them around deep idle methods.
(hw_perf_enable_all() is cheap on x86.)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 22c4469..5031b56 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -156,6 +156,8 @@
extern void perf_counter_init_task(struct task_struct *task);
extern void perf_counter_notify(struct pt_regs *regs);
extern void perf_counter_print_debug(void);
+extern void hw_perf_restore_ctrl(u64 ctrl);
+extern u64 hw_perf_disable_all(void);
#else
static inline void
perf_counter_task_sched_in(struct task_struct *task, int cpu) { }
@@ -166,6 +168,8 @@
static inline void perf_counter_init_task(struct task_struct *task) { }
static inline void perf_counter_notify(struct pt_regs *regs) { }
static inline void perf_counter_print_debug(void) { }
+static inline void hw_perf_restore_ctrl(u64 ctrl) { }
+static inline u64 hw_perf_disable_all(void) { return 0; }
#endif
#endif /* _LINUX_PERF_COUNTER_H */