Re: [PATCH 4/5] x86/kernel: Provide a means to disable TSC ART

[Peter Zijlstra]

On Mon, Oct 02, 2017 at 10:12:18AM -0500, mike.travis@xxxxxxx wrote:
>  static void detect_art(void)
>  {
>  	unsigned int unused[2];
>  
> -	if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF)
> +	if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF || tsc_art_disabled)
>  		return;
>  
>  	/* Don't enable ART in a VM, non-stop TSC and TSC_ADJUST required */


So why can't we use is_uv_system() here an for the tsc_adjust thing?

Also (and I hate the name) tsc_multi_sync_resets is the reason you
cannot use ART, I don't think it makes sense to introduce yet another
knob.