linux-kernel - Re: [PATCH v7 12/13] selftests/resctrl: Disable MBA and MBM tests for AMD

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Message-ID: <f80600a0-9d8c-a50f-5139-508d10ec4b20@amd.com>
Date:   Tue, 14 May 2019 17:17:07 +0000
From:   "Moger, Babu" <Babu.Moger@....com>
To:     "Yu, Fenghua" <fenghua.yu@...el.com>,
        Andre Przywara <andre.przywara@....com>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "Shen, Xiaochen" <xiaochen.shen@...el.com>,
        "Pathan, Arshiya Hayatkhan" <arshiya.hayatkhan.pathan@...el.com>,
        "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        James Morse <James.Morse@....com>
Subject: Re: [PATCH v7 12/13] selftests/resctrl: Disable MBA and MBM tests for
 AMD

Fenghua/Andre,


On 5/10/19 2:29 PM, Yu, Fenghua wrote:
> [CAUTION: External Email]
> 
>> On Friday, May 10, 2019 10:40 AM
>> Andre Przywara [mailto:andre.przywara@....com] wrote:
>> To: Yu, Fenghua <fenghua.yu@...el.com>
>> Cc: Thomas Gleixner <tglx@...utronix.de>; Ingo Molnar
>> <mingo@...hat.com>; Borislav Petkov <bp@...en8.de>; H Peter Anvin
>> <hpa@...or.com>; Luck, Tony <tony.luck@...el.com>; Chatre, Reinette
>> <reinette.chatre@...el.com>; Shankar, Ravi V <ravi.v.shankar@...el.com>;
>> Shen, Xiaochen <xiaochen.shen@...el.com>; Pathan, Arshiya Hayatkhan
>> <arshiya.hayatkhan.pathan@...el.com>; Prakhya, Sai Praneeth
>> <sai.praneeth.prakhya@...el.com>; Babu Moger <babu.moger@....com>;
>> linux-kernel <linux-kernel@...r.kernel.org>; James Morse
>> <James.Morse@....com>
>> Subject: Re: [PATCH v7 12/13] selftests/resctrl: Disable MBA and MBM tests
>> for AMD
>>
>> On Sat,  9 Feb 2019 18:50:41 -0800
>> Fenghua Yu <fenghua.yu@...el.com> wrote:
>>
>> Hi,
>>
>>> From: Babu Moger <babu.moger@....com>
>>>
>>> For now, disable MBA and MBM tests for AMD. Deciding test pass/fail is
>>> not clear right now. We can enable when we have some clarity.
>>
>> I don't think this is the right way. The availability of features should be
>> queryable, for instance by looking into /sys/fs/resctrl/info. Checking for a
>> certain vendor to skip tests just sounds wrong to me, and is definitely not
>> scalable or future proof.
>>
>> We should really check the availability of a feature, then skip the whole
>> subsystem test in resctrl_tests.c.
> 
> Babu may correct if I'm wrong: AMD does support the MBA and MBM features. So if querying the info directory, the features are there. But AMD doesn't want to support the testing for the features in the current patch set. They may support the testing in the future.

Yes. AMD supports the MBA and MBM features. But, deciding the test
pass/fail was not clear to me. That is why I decided to disable the test
for now. Right now, it reports the test result as "fail". We can add the
test in the future with some modifications.

> 
> Thanks.
> 
> -Fenghua
>