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

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Date:   Thu, 1 Nov 2018 14:55:36 +0000
From:   "Moger, Babu" <Babu.Moger@....com>
To:     Fenghua Yu <fenghua.yu@...el.com>
CC:     "tglx@...utronix.de" <tglx@...utronix.de>,
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Subject: RE: [PATCH v5 00/13] arch/x86: AMD QoS support

Fenghua,

> -----Original Message-----
> From: linux-kernel-owner@...r.kernel.org <linux-kernel-
> owner@...r.kernel.org> On Behalf Of Fenghua Yu
> Sent: Wednesday, October 31, 2018 4:55 PM
> To: Moger, Babu <Babu.Moger@....com>
> Cc: tglx@...utronix.de; mingo@...hat.com; bp@...en8.de; corbet@....net;
> reinette.chatre@...el.com; peterz@...radead.org;
> gregkh@...uxfoundation.org; davem@...emloft.net; akpm@...ux-
> foundation.org; hpa@...or.com; x86@...nel.org;
> mchehab+samsung@...nel.org; arnd@...db.de;
> kstewart@...uxfoundation.org; pombredanne@...b.com;
> rafael@...nel.org; kirill.shutemov@...ux.intel.com; tony.luck@...el.com;
> qianyue.zj@...baba-inc.com; xiaochen.shen@...el.com;
> pbonzini@...hat.com; Singh, Brijesh <brijesh.singh@....com>; Hurwitz,
> Sherry <sherry.hurwitz@....com>; dwmw2@...radead.org; Lendacky,
> Thomas <Thomas.Lendacky@....com>; luto@...nel.org; joro@...tes.org;
> jannh@...gle.com; vkuznets@...hat.com; rian@...m.mit.edu;
> jpoimboe@...hat.com; linux-kernel@...r.kernel.org; linux-
> doc@...r.kernel.org
> 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@...el.com>
> 
> 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;