linux-kernel - Re: [PATCH v5 6/8] x86/resctrl: Sub NUMA Cluster detection and enable

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Message-ID: <50e1be65-8f27-c290-94b8-7dd1d98dc663@intel.com>
Date:   Tue, 26 Sep 2023 14:03:27 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     "Luck, Tony" <tony.luck@...el.com>,
        "babu.moger@....com" <babu.moger@....com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>,
        "x86@...nel.org" <x86@...nel.org>
CC:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>
Subject: Re: [PATCH v5 6/8] x86/resctrl: Sub NUMA Cluster detection and enable

Hi Tony,

On 9/26/2023 12:40 PM, Luck, Tony wrote:
>>> +#include <linux/mod_devicetable.h>
>>
>> I didn't see the need for this include.
> 
> struct x86_cpu_id is defined in this #include file.
> 
>>> +static void snc_remap_rmids(int cpu)
>>
>> While adding the new functions, i see that new function names start with
>> resctrl_ prefix.  However, we are all not very consistent. Can ypu rename
>> this function to resctrl_snc_remap_rmids?
> 
> I try to put a subsystem prefix on any global symbols to avoid random
> conflicts in other parts of the kernel. But I'm less sure of the value for
> static functions and variables that are only visible inside a single ".c"
> file.
> 
> If it must have a prefix, should it be "intel_" rather than "resctrl_" to
> indicate that it is an Intel specific function?
> 
> 
>>> +static __init int get_snc_config(void)
>>
>> Same comment as above.
> 
> Same answer.
> 
> 
> Reinette: Any opinions on these?
> 

I agree with you that a consistent prefix is expected from the global
symbols and a prefix of resctrl_ is indeed the goal as can be seen in
the growing include/linux/resctrl.h. resctrl has no established pattern
for static functions (look at the other static functions in this file
being changed) or even those non-static functions and data
structures shared between the resctrl files (see
arch/x86/kernel/cpu/resctrl/internal.h).

I'm ok with the static functions named snc_remap_rmids() and get_snc_config().

We can surely start a discussion if there is concern about resctrl static
function prefixes but that discussion will have larger scope than
this series.

If we do want to focus on function naming I do think a change that may
benefit this work is to be consistent with verb placement in the function
names. i.e either always have verb first or have a consistent snc_ prefix
followed by a verb. I do not recall if there are x86 requirements in this
regard.

Reinette