perf, cpu hotplug: Use cached value of smp_processor_id()

The perf_cpu_notifier() macro invokes smp_processor_id()
multiple times. Optimize it by using a local variable.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: peterz@infradead.org
Cc: acme@ghostprotocols.net
Link: http://lkml.kernel.org/r/20121016075817.3572.76733.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 06478056da03f21d958b0a46f41a2b5c8b4b43c1..6bfb2faa0b1937555f5ca8fa937c7007bf5b3bc4 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -803,15 +803,16 @@ static inline void perf_event_task_tick(void)                             { }
 do {                                                                   \
        static struct notifier_block fn##_nb __cpuinitdata =            \
                { .notifier_call = fn, .priority = CPU_PRI_PERF };      \
+       unsigned long cpu = smp_processor_id();                         \
        unsigned long flags;                                            \
        fn(&fn##_nb, (unsigned long)CPU_UP_PREPARE,                     \
-               (void *)(unsigned long)smp_processor_id());             \
+               (void *)(unsigned long)cpu);                            \
        local_irq_save(flags);                                          \
        fn(&fn##_nb, (unsigned long)CPU_STARTING,                       \
-               (void *)(unsigned long)smp_processor_id());             \
+               (void *)(unsigned long)cpu);                            \
        local_irq_restore(flags);                                       \
        fn(&fn##_nb, (unsigned long)CPU_ONLINE,                         \
-               (void *)(unsigned long)smp_processor_id());             \
+               (void *)(unsigned long)cpu);                            \
        register_cpu_notifier(&fn##_nb);                                \
 } while (0)