On Tue, Nov 19, 2013 at 01:06:30PM -0800, Jacob Pan wrote: > On Tue, 19 Nov 2013 16:13:38 +0100 > Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > On Tue, Nov 19, 2013 at 03:51:43PM +0100, Peter Zijlstra wrote: > > > That said, that drive is completely wrecked. It uses > > > preempt_enable_no_resched() wrong too, it has uncommented barriers.. > > > > > > Dude, wtf are you guys smoking? > > > I applied this patch on top of upstream kernel (801a760) and found out > my machine completely failed to enter idle when nothing is running. > turbostate shows 100% C0. ftrace shows kernel coming in and out of idle > frequently. > > Both ACPI idle and intel_idle behaves the same way. I have to do the > following change to allow entering C-states again. > > diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h > index 80014da..b51d1e1 100644 > --- a/arch/x86/include/asm/mwait.h > +++ b/arch/x86/include/asm/mwait.h > @@ -49,10 +49,8 @@ static inline void mwait_idle_with_hints(unsigned > long eax, unsigned long ecx) clflush((void > *)¤t_thread_info()->flags); > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!current_set_polling_and_test()) > + if (!need_resched()) > __mwait(eax, ecx); > - > - __current_clr_polling(); > } > > #endif /* _ASM_X86_MWAIT_H */ That doesn't make any sense; current_set_polling_and_test() returns the same thing need_resched() does. But you're right, intel_idle resides 100% in C0 and acpi_idle has 100% C1 residency... most weird. /me goes prod at it -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
