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SubjectRE: [PATCH v5 00/13] arch/x86: AMD QoS support
Date
Fenghua,

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org <linux-kernel-
> owner@vger.kernel.org> On Behalf Of Fenghua Yu
> Sent: Wednesday, October 31, 2018 4:55 PM
> To: Moger, Babu <Babu.Moger@amd.com>
> Cc: tglx@linutronix.de; mingo@redhat.com; bp@alien8.de; corbet@lwn.net;
> reinette.chatre@intel.com; peterz@infradead.org;
> gregkh@linuxfoundation.org; davem@davemloft.net; akpm@linux-
> foundation.org; hpa@zytor.com; x86@kernel.org;
> mchehab+samsung@kernel.org; arnd@arndb.de;
> kstewart@linuxfoundation.org; pombredanne@nexb.com;
> rafael@kernel.org; kirill.shutemov@linux.intel.com; tony.luck@intel.com;
> qianyue.zj@alibaba-inc.com; xiaochen.shen@intel.com;
> pbonzini@redhat.com; Singh, Brijesh <brijesh.singh@amd.com>; Hurwitz,
> Sherry <sherry.hurwitz@amd.com>; dwmw2@infradead.org; Lendacky,
> Thomas <Thomas.Lendacky@amd.com>; luto@kernel.org; joro@8bytes.org;
> jannh@google.com; vkuznets@redhat.com; rian@alum.mit.edu;
> jpoimboe@redhat.com; linux-kernel@vger.kernel.org; linux-
> doc@vger.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@intel.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;

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