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| author |   Ingo Molnar <mingo@elte.hu> | 2008-05-14 08:47:40 +0200 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2008-05-17 22:57:20 +0200 |
| commit | a738d897b7b03b83488ae74a9bc03d26a2875dc6 (patch) | |
| tree | a5eadb80fb893a36d3653fd9cfc0ba5acaa0e30b /arch/x86/kernel/process.c | |
| parent | Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc (diff) | |
| download | linux-dev-a738d897b7b03b83488ae74a9bc03d26a2875dc6.tar.xz linux-dev-a738d897b7b03b83488ae74a9bc03d26a2875dc6.zip | |
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>
Diffstat (limited to 'arch/x86/kernel/process.c')
| -rw-r--r-- | arch/x86/kernel/process.c | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 67e9b4a1e89d..c7b6a694ca22 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -99,15 +99,6 @@ static void mwait_idle(void) local_irq_enable(); } - -static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c) -{ - if (force_mwait) - return 1; - /* Any C1 states supported? */ - return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0; -} - /* * On SMP it's slightly faster (but much more power-consuming!) * to poll the ->work.need_resched flag instead of waiting for the @@ -131,7 +122,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) " performance may degrade.\n"); } #endif - if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) { + if (cpu_has(c, X86_FEATURE_MWAIT)) { /* * Skip, if setup has overridden idle. * One CPU supports mwait => All CPUs supports mwait |