linux-kernel - RE: [PATCH 3/7] x86/resctrl: Add a new node-scoped resource to rdt_resources

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

Message-ID: <SJ1PR11MB608302C99598570098E40102FCCC9@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date:   Fri, 27 Jan 2023 18:23:19 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        "Jonathan Corbet" <corbet@....net>,
        "x86@...nel.org" <x86@...nel.org>
CC:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        "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 3/7] x86/resctrl: Add a new node-scoped resource to
 rdt_resources_all[]

>> +	[RDT_RESOURCE_NODE] =
>> +	{
>> +		.r_resctrl = {
>> +			.rid			= RDT_RESOURCE_NODE,
>> +			.name			= "L3",

> "L3" was named as RDT_RESOURCE_L3 already. The duplicate name here may
> cause duplicate file names in info dir. Maybe rename it as "L3_NODE"?

I thought the same, and my first implementation used a different string here (I picked
"NODE" rather than "L3_NODE").

But my testers complained that this broke all their existing infrastructure that reads
cache occupancy and memory bandwidth. This string is not just used in the info/
directory, it is also the basis for the directory names in mon_data/

$ tree /sys/fs/resctrl/mon_data
/sys/fs/resctrl/mon_data
├── mon_L3_00
│   ├── llc_occupancy
│   ├── mbm_local_bytes
│   └── mbm_total_bytes
├── mon_L3_01
│   ├── llc_occupancy
│   ├── mbm_local_bytes
│   └── mbm_total_bytes
├── mon_L3_02
│   ├── llc_occupancy
│   ├── mbm_local_bytes
│   └── mbm_total_bytes
└── mon_L3_03
    ├── llc_occupancy
    ├── mbm_local_bytes
    └── mbm_total_bytes

The name using "L3" is still appropriate and accurate.

There isn't a "duplicate file names" problem in the info/ directory because a system
either has SNC disabled, and uses the L3-scoped resource, or has SNC enabled and
uses the node-scoped resource.

-Tony