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Date: Mon, 02 Apr 2012 19:36:45 +0530 From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> To: lenb@...nel.org Cc: venki@...gle.com, suresh.b.siddha@...el.com, bp@...64.org, tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, x86@...nel.org, ben@...adent.org.uk, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>, deepthi@...ux.vnet.ibm.com Subject: [PATCH] x86: Make mwait_usable() respect "idle=nomwait" kernel parameter mwait_usable() returns 1 even if the "idle=nomwait" kernel parameter is passed. Fix it by adding a check for boot_option_idle_override == IDLE_NOMWAIT and returning 0 if it is set. Before applying the patch (dmesg snippet): [ 0.000000] Command line: [...] idle=nomwait [ 0.000000] Kernel command line: [...] idle=nomwait [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 0.140606] using mwait in idle threads. <======= mwait being used [ 4.303986] cpuidle: using governor ladder [ 4.308232] cpuidle: using governor menu After applying the patch: [ 0.000000] Command line: [...] idle=nomwait [ 0.000000] Kernel command line: [...] idle=nomwait [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 4.264100] cpuidle: using governor ladder [ 4.268342] cpuidle: using governor menu Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com> --- arch/x86/kernel/process.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index a33afaa..945fbf0 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -621,6 +621,9 @@ int mwait_usable(const struct cpuinfo_x86 *c) if (boot_option_idle_override == IDLE_FORCE_MWAIT) return 1; + if (boot_option_idle_override == IDLE_NOMWAIT) + return 0; + if (c->cpuid_level < MWAIT_INFO) return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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