linux-kernel - Re: [PATCH v8 6/8] x86/resctrl: Move default group file creation to mount

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Message-ID: <f33d96b1-ef46-f1fd-94e3-52baab2fd29f@intel.com>
Date:   Fri, 1 Sep 2023 16:36:59 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>, Babu Moger <babu.moger@....com>,
        <corbet@....net>, <tglx@...utronix.de>, <mingo@...hat.com>,
        <bp@...en8.de>
CC:     <dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
        <paulmck@...nel.org>, <akpm@...ux-foundation.org>,
        <quic_neeraju@...cinc.com>, <rdunlap@...radead.org>,
        <damien.lemoal@...nsource.wdc.com>, <songmuchun@...edance.com>,
        <peterz@...radead.org>, <jpoimboe@...nel.org>,
        <pbonzini@...hat.com>, <chang.seok.bae@...el.com>,
        <pawan.kumar.gupta@...ux.intel.com>, <jmattson@...gle.com>,
        <daniel.sneddon@...ux.intel.com>, <sandipan.das@....com>,
        <tony.luck@...el.com>, <james.morse@....com>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <bagasdotme@...il.com>, <eranian@...gle.com>,
        <christophe.leroy@...roup.eu>, <jarkko@...nel.org>,
        <adrian.hunter@...el.com>, <quic_jiles@...cinc.com>,
        <peternewman@...gle.com>
Subject: Re: [PATCH v8 6/8] x86/resctrl: Move default group file creation to
 mount

Hi Fenghua,

On 9/1/2023 4:21 PM, Fenghua Yu wrote:
> On 8/21/23 16:30, Babu Moger wrote:
>> The default resource group and its files are created during kernel
>> init time. Upcoming changes will make some resctrl files optional
>> based on a mount parameter. If optional files are to be added to the
>> default group based on the mount option, then each new file needs to
>> be created separately and call kernfs_activate() again.
>>
>> Create all files of the default resource group during resctrl
>> mount, destroyed during unmount, to avoid scattering resctrl
>> file addition across two separate code flows.
>>
>> Suggested-by: Reinette Chatre <reinette.chatre@...el.com>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>>   arch/x86/kernel/cpu/resctrl/internal.h |  2 +
>>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 55 +++++++++++++++-----------
>>   2 files changed, 33 insertions(+), 24 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index b09e7abd1299..44ad98f8c7af 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -611,5 +611,7 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
>>   void __init thread_throttle_mode_init(void);
>>   void __init mbm_config_rftype_init(const char *config);
>>   void rdt_staged_configs_clear(void);
>> +int rdtgroup_setup_root(struct rdt_fs_context *ctx);
>> +void rdtgroup_destroy_root(void);
> 
> These two functions are called only in rdtgroup.c. Why are they exposed here?
> 

Could you please take a look at the email thread [1] that
discusses this? We reached a compromise but would appreciate
if you have any guidance on the right solution.

Reinette

[1] https://lore.kernel.org/lkml/972db626-1d74-679d-72f2-3e122f95c314@intel.com/