smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()

While trying to initialize idle threads for all cpus, idle_threads_init()
calls smp_processor_id() in a loop, which is unnecessary. The intent
is to initialize idle threads for all non-boot cpus. So just use a variable
to note the boot cpu and use it in the loop.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: suresh.b.siddha@intel.com
Cc: venki@google.com
Cc: nikunj@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20120524151055.2549.64309.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index e1a797e028a320d62c01e77a47f533e0998adaa3..0f2162f808a7d1973baac593db46f72ab0da46a6 100644 (file)
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -52,10 +52,12 @@ static inline void idle_init(unsigned int cpu)
  */
 void __init idle_threads_init(void)
 {
-       unsigned int cpu;
+       unsigned int cpu, boot_cpu;
+
+       boot_cpu = smp_processor_id();
 
        for_each_possible_cpu(cpu) {
-               if (cpu != smp_processor_id())
+               if (cpu != boot_cpu)
                        idle_init(cpu);
        }
 }