x86: remove mwait capability C-state check
authorIngo Molnar <mingo@elte.hu>
Wed, 14 May 2008 06:47:40 +0000 (08:47 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Sat, 17 May 2008 20:57:20 +0000 (22:57 +0200)
commita738d897b7b03b83488ae74a9bc03d26a2875dc6
treea5eadb80fb893a36d3653fd9cfc0ba5acaa0e30b
parentf26a3988917913b3d11b2bd741601a2c64ab9204
x86: remove mwait capability C-state check

Vegard Nossum reports:

| powertop shows between 200-400 wakeups/second with the description
| "<kernel IPI>: Rescheduling interrupts" when all processors have load (e.g.
| I need to run two busy-loops on my 2-CPU system for this to show up).
|
| The bisect resulted in this commit:
|
| commit 0c07ee38c9d4eb081758f5ad14bbffa7197e1aec
| Date:   Wed Jan 30 13:33:16 2008 +0100
|
|     x86: use the correct cpuid method to detect MWAIT support for C states

remove the functional effects of this patch and make mwait unconditional.

A future patch will turn off mwait on specific CPUs where that causes
power to be wasted.

Bisected-by: Vegard Nossum <vegard.nossum@gmail.com>
Tested-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/kernel/process.c