[PATCH] Re: Performance issue in 2.5.32+

- The early startup code was changed so smp_prepare_cpus() is now called
  before do_basic_setup().  do_basic_setup() is where mtrr_init() is
  called, which mtrr_init_secondary_cpu() is dependent on being called.

- mtrr_init_boot_cpu() was removed from the AP startup code. This was a
  SMP-only hack that made sure mtrr_init() happened when SMP was
  enabled.  That's right - two different code paths to do the same
  thing, obscured by compile-time defines.

The appended patch makes sure mtrr_init() is called before
smp_prepare_cpus(). It's ugly, and I'll work on a cleaner solution, but
James: could you try it and see if it fixes your performance issues?

init/main.c

@@ -490,15 +490,6 @@ static void __init do_initcalls(void)
  */
 static void __init do_basic_setup(void)
 {
-#if defined(CONFIG_MTRR)	/* Do this after SMP initialization */
-/*
- * We should probably create some architecture-dependent "fixup after
- * everything is up" style function where this would belong better
- * than in init/main.c..
- */
-	mtrr_init();
-#endif
-
 #ifdef CONFIG_SYSCTL
 	sysctl_init();
 #endif
@@ -545,6 +536,15 @@ static int init(void * unused)
 	 */
 	child_reaper = current;
 
+#if defined(CONFIG_MTRR)	/* Do this after SMP initialization */
+/*
+ * We should probably create some architecture-dependent "fixup after
+ * everything is up" style function where this would belong better
+ * than in init/main.c..
+ */
+	mtrr_init();
+#endif
+
 	/* Sets up cpus_possible() */
 	smp_prepare_cpus(max_cpus);