linux-kernel - Re: [PATCH v2 5/7] x86/resctrl: Add interface to enable/disable io

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Message-ID: <dfc63874-9150-41de-959e-cb782257e580@intel.com>
Date: Mon, 23 Dec 2024 11:32:49 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: "Luck, Tony" <tony.luck@...el.com>, Babu Moger <babu.moger@....com>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com"
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Subject: Re: [PATCH v2 5/7] x86/resctrl: Add interface to enable/disable
 io_alloc feature

Hi Tony,

On 12/18/24 3:34 PM, Luck, Tony wrote:
>> static void rdt_get_sdciae_alloc_cfg(struct rdt_resource *r)
>>  {
>>       r->cache.io_alloc_capable = true;
>> +     resctrl_file_fflags_init("io_alloc",
>> +                              RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE);
>>  }
> 
> I think those fflags will make this file appear in all info cache directories
> (L2 and L3).
> 
> Presumably you only want this file (and "io_alloc_cbm" added by next
> patch) in the L3 directory.

Could you please elaborate why this file should only be in L3 directory? I do not see
the problem with having it in L2. "io_alloc" communicates to user space if this I/O alloc
feature is supported and does so with its content as opposed to its existence. For L2
it will indicate that the feature is not supported.

Reinette