linux-kernel - Re: [PATCH v2 3/4] Documentation/x86: Document resctrl's new sparse

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Message-ID: <90303d4b-113d-9adc-14cb-d55c7a24f4af@amd.com>
Date:   Thu, 28 Sep 2023 08:59:38 -0500
From:   "Moger, Babu" <babu.moger@....com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Jonathan Corbet <corbet@....net>
Cc:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 3/4] Documentation/x86: Document resctrl's new
 sparse_masks



On 9/27/23 18:02, Fenghua Yu wrote:
> 
> 
> On 9/27/23 15:58, Reinette Chatre wrote:
>> Hi Babu,
>>
>> On 9/27/2023 3:47 PM, Moger, Babu wrote:
>>> On 9/22/2023 3:48 AM, Maciej Wieczor-Retman wrote:
>>>> From: Fenghua Yu <fenghua.yu@...el.com>
>>>>
>>>> The documentation mentions that non-contiguous bit masks are not
>>>> supported in Intel Cache Allocation Technology (CAT).
>>>>
>>>> Update the documentation on how to determine if sparse bit masks are
>>>> allowed in L2 and L3 CAT.
>>>>
>>>> Mention the file with feature support information is located in
>>>> the /sys/fs/resctrl/info/{resource}/ directories and enumerate what
>>>> are the possible outputs on file read operation.
>>>>
>>>> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
>>>> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
>>>> ---
>>>> Changelog v2:
>>>> - Change bitmap naming convention to bit mask. (Reinette)
>>>>
>>>>    Documentation/arch/x86/resctrl.rst | 16 ++++++++++++----
>>>>    1 file changed, 12 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/Documentation/arch/x86/resctrl.rst
>>>> b/Documentation/arch/x86/resctrl.rst
>>>> index cb05d90111b4..4c6421e2aa31 100644
>>>> --- a/Documentation/arch/x86/resctrl.rst
>>>> +++ b/Documentation/arch/x86/resctrl.rst
>>>> @@ -124,6 +124,13 @@ related to allocation:
>>>>                "P":
>>>>                      Corresponding region is pseudo-locked. No
>>>>                      sharing allowed.
>>>> +"sparse_masks":
>>>> +        Indicates if non-contiguous 1s value in CBM is supported.
>>>> +
>>>> +            "0":
>>>> +                  Only contiguous 1s value in CBM is supported.
>>>
>>> This is little confusing. How about?
>>>
>>> Non-contiguous 1s value in CBM is not supported
>>>
>>
>> It is not clear to me how changing it to a double
>> negative reduces confusion.
> Agree with Reinette.
> 
> The original statement is clearer and more direct to explicitly state what
> is supported without introducing a negative assertion (not supported).

Ok. If you all agree, fine with me as well.

-- 
Thanks
Babu Moger