linux-kernel - Re: [PATCH 10/24] x86/resctrl: Move the schema names into struct resctrl

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Message-ID: <149b51e9-c6c5-3236-8a27-94846bd784df@arm.com>
Date:   Fri, 12 Mar 2021 17:38:07 +0000
From:   James Morse <james.morse@....com>
To:     Reinette Chatre <reinette.chatre@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        shameerali.kolothum.thodi@...wei.com,
        Jamie Iles <jamie@...iainc.com>,
        D Scott Phillips OS <scott@...amperecomputing.com>
Subject: Re: [PATCH 10/24] x86/resctrl: Move the schema names into struct
 resctrl_schema

Hi Reinette,

On 17/11/2020 23:11, Reinette Chatre wrote:
> On 10/30/2020 9:11 AM, James Morse wrote:
>> Move the names used for the schemata file out of the resource and
>> into struct resctrl_schema. This allows one resource to have two
>> different names, based on the other schema properties.
>>
>> This patch copies the names, eventually resctrl will generate them.
> 
> Please remove "This patch".
> 
>>
>> Remove the arch code's max_name_width, this is now resctrl's
>> problem.

>> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
>> b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
>> index a65ff53394ed..28d69c78c29e 100644
>> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
>> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> 
> ...
> 
>> @@ -391,7 +389,7 @@ static void show_doms(struct seq_file *s, struct resctrl_schema
>> *schema, int clo
>>       bool sep = false;
>>       u32 ctrl_val;
>>   -    seq_printf(s, "%*s:", max_name_width, r->name);
>> +    seq_printf(s, "%*s:", RESCTRL_NAME_LEN, schema->name);
> 
> From what I understand this changes what some users will see. In the original code the
> "max_name_width" is computed based on the maximum length of resources supported. Systems
> that only support MBA would thus show a schemata of:
> 
> MB:0=100;1=100
> 
> I expect the above change would change the output to:
>     MB:0=100;1=100

Aha! Despite the comment - I've totally miss-understood what this code is doing.


Thanks!

James