linux-kernel - Re: RE: [PATCH v8 08/25] x86/resctrl: Introduce interface to display number of monitoring counters

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <c3c3953b-d069-40d3-e7e0-db8c0e7eef40@amd.com>
Date: Fri, 25 Oct 2024 15:31:30 -0500
From: "Moger, Babu" <bmoger@....com>
To: "Luck, Tony" <tony.luck@...el.com>,
 "babu.moger@....com" <babu.moger@....com>,
 "Chatre, Reinette" <reinette.chatre@...el.com>
Cc: "corbet@....net" <corbet@....net>, "Yu, Fenghua" <fenghua.yu@...el.com>,
 "tglx@...utronix.de" <tglx@...utronix.de>,
 "mingo@...hat.com" <mingo@...hat.com>, "bp@...en8.de" <bp@...en8.de>,
 "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
 "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
 "paulmck@...nel.org" <paulmck@...nel.org>,
 "rdunlap@...radead.org" <rdunlap@...radead.org>,
 "tj@...nel.org" <tj@...nel.org>, "peterz@...radead.org"
 <peterz@...radead.org>, "yanjiewtw@...il.com" <yanjiewtw@...il.com>,
 "kim.phillips@....com" <kim.phillips@....com>,
 "lukas.bulwahn@...il.com" <lukas.bulwahn@...il.com>,
 "seanjc@...gle.com" <seanjc@...gle.com>,
 "jmattson@...gle.com" <jmattson@...gle.com>,
 "leitao@...ian.org" <leitao@...ian.org>,
 "jpoimboe@...nel.org" <jpoimboe@...nel.org>,
 "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
 "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
 "Joseph, Jithu" <jithu.joseph@...el.com>, "Huang, Kai"
 <kai.huang@...el.com>, "kan.liang@...ux.intel.com"
 <kan.liang@...ux.intel.com>,
 "daniel.sneddon@...ux.intel.com" <daniel.sneddon@...ux.intel.com>,
 "pbonzini@...hat.com" <pbonzini@...hat.com>,
 "sandipan.das@....com" <sandipan.das@....com>,
 "ilpo.jarvinen@...ux.intel.com" <ilpo.jarvinen@...ux.intel.com>,
 "peternewman@...gle.com" <peternewman@...gle.com>,
 "Wieczor-Retman, Maciej" <maciej.wieczor-retman@...el.com>,
 "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "Eranian, Stephane" <eranian@...gle.com>,
 "james.morse@....com" <james.morse@....com>
Subject: Re: RE: [PATCH v8 08/25] x86/resctrl: Introduce interface to display
 number of monitoring counters

Hi Tony,

On 10/24/2024 12:37 PM, Luck, Tony wrote:
>>>> Since you seem to want to keep the flexibility for a possible future
>>>> where per-domain is needed. The "available_mbm_cntrs" file
>>>> suggested in another thread would need to list available counters
>>>> on each domain to avoid ABI problems should that future arrive.
>>>>
>>>> $ cat num_mbm_counters
>>>> 32
>>>>
>>>> $ cat available_mbm_cntrs
>>>> 0=12;1=9
>>>
>>> Good point.
>>>
>>
>> Working on this now. Wanted to confirm if we really need domain specific
>> information?
>>
>> To me, it does not seem necessary for the user. User cannot make any
>> decisions based on this information.
>>
>> All user wants to know is if there are global counters available.
>>
>> $ cat num_mbm_counters
>> 32
>>
>> $ cat available_mbm_cntrs
>> 15
> 
> This approach paints resctrl into an ABI corner where it can't later
> update resctrl to track counters per-domain. Maybe you'll never want to do that,
> but some other architecture might want to have that flexibility.

Ok. Fine. Lets keep the per-domain counters.

-- 
- Babu Moger