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

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Message-ID: <bced7bc7-c489-7a57-374f-62818cbfded6@intel.com>
Date:   Wed, 27 Sep 2023 15:58:33 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     <babu.moger@....com>,
        Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
        Fenghua Yu <fenghua.yu@...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

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.

Reinette