[PATCH] x86: Don't use MWAIT on AMD Family 10

It doesn't put the CPU into deeper sleep states, so it's better to use the standard
idle loop to save power. But allow to reenable it anyways for benchmarking.

I also removed the obsolete idle=halt on i386

Cc: andreas.herrmann@amd.com

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 9 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4287696f18dd..94ce0d20253d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -695,8 +695,15 @@ and is between 256 and 4096 characters. It is defined in the file
         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
                         See Documentation/ide.txt.
 
-        idle=           [HW]
-                        Format: idle=poll or idle=halt
+        idle=           [X86]
+                        Format: idle=poll or idle=mwait
+                        Poll forces a polling idle loop that can slightly improves the performance
+                        of waking up a idle CPU, but will use a lot of power and make the system
+                        run hot. Not recommended.
+                        idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
+                        to not use it because it doesn't save as much power as a normal idle
+                        loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
+                        as idle=poll.
 
         ignore_loglevel [KNL]
                         Ignore loglevel setting - this will print /all/