On Thu, Dec 19, 2013 at 08:13:21AM -0800, H. Peter Anvin wrote:
> How does this look? Completely untested, of course.
>
> I do wonder if we need more memory barriers, though.
>
> An alternative would be to move everything into mwait_idle_with_hints().
>
> -hpa
>
> diff --git a/arch/x86/include/asm/processor.h
> b/arch/x86/include/asm/processor.h
> index 7b034a4057f9..6dce588f94b4 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -723,6 +723,23 @@ static inline void __sti_mwait(unsigned long eax,
> unsigned long ecx)
> :: "a" (eax), "c" (ecx));
> }
>
> +/*
> + * Issue a clflush in preparation for a monitor instruction if the CPU
> + * needs it. We force the address into the ax register to get a fixed
> + * length for the instruction, however, this is what the monitor instruction
> + * is going to need anyway, so it shouldn't add any additional code.
> + */
> +static inline void clflush_monitor(const void *addr, unsigned long ecx,
> + unsigned long edx)
> +{
> + alternative_input(ASM_NOP3,
> + "clflush (%0)",
> + X86_FEATURE_CLFLUSH_MONITOR,
> + "a" (addr));
> + __monitor(addr, eax, edx);
> + smp_mb();
> +}
What's that mb for?
Also, can you please merge:
http://marc.info/?l=linux-kernel&m=138685838420632
Thomas said he would pick up that series, but seems to have gone missing
the past week or so.
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