RE: [PATCH v5 00/13] arch/x86: AMD QoS support

[Moger, Babu]

Fenghua,

> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx <linux-kernel-
> owner@xxxxxxxxxxxxxxx> On Behalf Of Fenghua Yu
> Sent: Wednesday, October 31, 2018 4:55 PM
> To: Moger, Babu <Babu.Moger@xxxxxxx>
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> Subject: Re: [PATCH v5 00/13] arch/x86: AMD QoS support
> 
> On Thu, Oct 18, 2018 at 10:52:00PM +0000, Moger, Babu wrote:
> > Changes from v4 -> v5:
> >  b. The functions update_mba_bw and set_mba_sc is not required for
> AMD.
> >     Removed all the changes related to these functions.
> 
> Hi, Babu,
> 
> In v4, you says AMD won't support MBA software controller.
> 
> In v5, does AMD support MBA software controller or not? The v5 patches

No, AMD does not support MBA software controller. set_mba_sc will always
return -EINVAL on AMD(because delay_linear is set false). That is the
reason, I did not add this check. I will add this check in next refresh.
Will add Suggested-by you. Thanks

> show the feature is supported now. If that's a code bug, you may need
> the following patch?
> 
> x86/resctrl: Only Intel RDT supports MBA software controller
> 
> AMD doesn't support the feature.
> 
> Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> 
> diff --git a/arch/x86/kernel/cpu/resctrl_rdtgroup.c
> b/arch/x86/kernel/cpu/resctrl_rdtgroup.c
> index 8b6b4a8bb7ca..89dd9b7c9dd7 100644
> --- a/arch/x86/kernel/cpu/resctrl_rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl_rdtgroup.c
> @@ -1878,9 +1878,11 @@ static int parse_rdtgroupfs_options(char *data)
>  			if (ret)
>  				goto out;
>  		} else if (!strcmp(token, "mba_MBps")) {
> -			ret = set_mba_sc(true);
> -			if (ret)
> -				goto out;
> +			if (boot_cpu_data.x86_vendor ==
> X86_VENDOR_INTEL) {
> +				ret = set_mba_sc(true);
> +				if (ret)
> +					goto out;
> +			}
>  		} else {
>  			ret = -EINVAL;
>  			goto out;