From mboxrd@z Thu Jan 1 00:00:00 1970 From: Deepthi Dharwar Subject: Re: [PATCH 1/3] cpuidle: If disable_cpuidle() is called, set pm_idle to default_idle. Date: Wed, 09 Nov 2011 15:49:49 +0530 Message-ID: <4EBA53C5.9040603@linux.vnet.ibm.com> References: <1320786914-10541-1-git-send-email-konrad.wilk@oracle.com> <1320786914-10541-2-git-send-email-konrad.wilk@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1320786914-10541-2-git-send-email-konrad.wilk@oracle.com> Sender: linux-kernel-owner@vger.kernel.org To: Konrad Rzeszutek Wilk Cc: linux-kernel@vger.kernel.org, x86@kernel.org, len.brown@intel.com, tglx@linutronix.de, jeremy@goop.org, hpa@zytor.com, bp@alien8.de, tj@kernel.org, trenn@suse.de, mingo@redhat.com, xen-devel@lists.xensource.com, stable@kernel.org List-Id: xen-devel@lists.xenproject.org On Wednesday 09 November 2011 02:45 AM, Konrad Rzeszutek Wilk wrote: > . however we ignore the disable_cpuidle() directive and > in select_idle_routine() set it to type preferred by the CPU. > > This is a regression introduced by > > commit a0bfa1373859e9d11dc92561a8667588803e42d8 > Author: Len Brown > Date: Fri Apr 1 19:34:59 2011 -0400 > > cpuidle: stop depending on pm_idle > > specifically this patch: > > commit d91ee5863b71e8c90eaf6035bff3078a85e2e7b5 > Author: Len Brown > Date: Fri Apr 1 18:28:35 2011 -0400 > > cpuidle: replace xen access to x86 pm_idle and default_idle > > ..scribble on pm_idle and access default_idle, > have it simply disable_cpuidle() so acpi_idle will not load and > architecture default HLT will be used. > > .. but the default HLT does not get used. Instead we end up in the > situation that select_idle_routine() is called from arch/x86/kernel/cpu/common.c > and if we called cpuidle_disable(), then the pm_idle is not set, and > we end up setting pm_idle to mwait_idle or amd_e400_idle. > > This patch uses the cpuidle_disabled() functionality and > makes select_idle_routine() adhere to that. > > Reported-by: Stefan Bader > Signed-off-by: Konrad Rzeszutek Wilk > > CC: Thomas Gleixner > CC: Ingo Molnar > CC: "H. Peter Anvin" > CC: x86@kernel.org > CC: Len Brown > CC: Borislav Petkov > CC: Tejun Heo > CC: Thomas Renninger > CC: stable@kernel.org > --- > arch/x86/kernel/process.c | 5 +++++ > include/linux/cpuidle.h | 2 ++ > 2 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index e7e3b01..1f7f8c8 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -587,6 +588,10 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) > if (pm_idle) > return; > > + if (cpuidle_disabled()) { > + pm_idle = default_idle; > + return; > + } The above check is needed to initialise pm_idle to default_idle if cpuidle is disabled but this requirement here is Zen specific. On other architectures, if cpuidle is disabled on boot then we rather would want mwait_idle or amd_e400_idle to be enabled than default_idle. Can we make this check Zen specific ? ... if(ZEN_ARCH && cpuidle_disabled()) ... > if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) { > /* > * One CPU supports mwait => All CPUs supports mwait > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h > index b51629e..123fe9e 100644 > --- a/include/linux/cpuidle.h > +++ b/include/linux/cpuidle.h > @@ -122,6 +122,7 @@ struct cpuidle_driver { > }; > > #ifdef CONFIG_CPU_IDLE > +extern int cpuidle_disabled(void); > extern void disable_cpuidle(void); > extern int cpuidle_idle_call(void); > > @@ -137,6 +138,7 @@ extern int cpuidle_enable_device(struct cpuidle_device *dev); > extern void cpuidle_disable_device(struct cpuidle_device *dev); > > #else > +static inline int cpuidle_disabled(void) { return 1; } > static inline void disable_cpuidle(void) { } > static inline int cpuidle_idle_call(void) { return -ENODEV; } >