From: Ingo Molnar Date: Wed, 14 May 2008 06:47:40 +0000 (+0200) Subject: x86: remove mwait capability C-state check X-Git-Tag: v2.6.26-rc3~21^2~2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a738d897b7b03b83488ae74a9bc03d26a2875dc6;p=linux-2.6 x86: remove mwait capability C-state check Vegard Nossum reports: | powertop shows between 200-400 wakeups/second with the description | ": 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 Tested-by: Vegard Nossum Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 67e9b4a1e8..c7b6a694ca 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