RE: [PATCH 4/4] selftests/resctrl: Adjust SNC support messages

From: "Luck, Tony" <tony.luck@intel.com>
To: "Chatre, Reinette" <reinette.chatre@intel.com>,
	"Wieczor-Retman, Maciej" <maciej.wieczor-retman@intel.com>
Cc: "Yu, Fenghua" <fenghua.yu@intel.com>,
	Shuah Khan <shuah@kernel.org>,
	"james.morse@arm.com" <james.morse@arm.com>,
	"ilpo.jarvinen@linux.intel.com" <ilpo.jarvinen@linux.intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-kselftest@vger.kernel.org"
	<linux-kselftest@vger.kernel.org>
Subject: RE: [PATCH 4/4] selftests/resctrl: Adjust SNC support messages
Date: Thu, 7 Mar 2024 21:14:35 +0000	[thread overview]
Message-ID: <SJ1PR11MB6083AACB10645E41DD3F9639FC202@SJ1PR11MB6083.namprd11.prod.outlook.com> (raw)
In-Reply-To: <0393c4ce-7e41-4dcc-940a-a6bea9437970@intel.com>

> Thinking about it even differently. The goal is to give information
> to userspace so we need to think about what would help user space?
> For example, what if there is a file in info that shows 
> which CPUs are associated with each domain?

Reinette,

Interesting idea. That would save users from having to chase through
/sys/devices/system/cpu/cpu*/cache/index?/* to figure out what the domain
numbers in schemata files and the mon_data/mon_L3_XX values mean.

May be extra useful for ARM which seems to have big random-looking numbers
for domains that came out of ACPI tables.

For SNC it would get the user directly to what they probably care about
(which CPUs are in which domain).

So something like this for an SNC 2 system:

$ cat /sys/fs/resctrl/info/L3/cpus
0: 0-35,72-107
1: 36-71,108-143

$ cat /sys/fs/resctrl/info/L3_MON/cpus
0: 0-17,72-89
1: 18-35,90-107
2: 36-53,108-125
3: 54-71,126-143

[maybe there is a better name than "cpus" for this file?]

-Tony