[Xen-devel] [PATCH 3/3] Disable ARB_DIS conditionally

["Wei, Gang" <gang.wei@xxxxxxxxx>]

CPUIDLE: Write to ARB_DISABLE conditionally to reduce some idle overheads.

Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>

diff -r 48ab8d09f41e xen/arch/x86/acpi/cpu_idle.c
--- a/xen/arch/x86/acpi/cpu_idle.c      Tue Sep 02 15:38:37 2008 +0800
+++ b/xen/arch/x86/acpi/cpu_idle.c      Tue Sep 02 16:03:09 2008 +0800
@@ -455,8 +455,9 @@ static void acpi_processor_idle(void)
         if ( power->flags.bm_check && power->flags.bm_control )
         {
             /* Enable bus master arbitration */
+            if ( atomic_read(&c3_cpu_count) == num_online_cpus() )
+                acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
             atomic_dec(&c3_cpu_count);
-            acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
         }

         /* Re-enable interrupts */

Attachment: disable-ARB_DIS-conditionally-0902.patch
Description: disable-ARB_DIS-conditionally-0902.patch

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