linux-kernel - [PATCH v2 0/3] x86/resctrl: Add "*" shorthand to set minimum io

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Message-ID: <20251215230257.1798865-1-atomlin@atomlin.com>
Date: Mon, 15 Dec 2025 18:02:54 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: tony.luck@...el.com,
	reinette.chatre@...el.com,
	Dave.Martin@....com,
	james.morse@....com,
	babu.moger@....com,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com
Cc: dave.martin@....com,
	atomlin@...mlin.com,
	sean@...e.io,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/3] x86/resctrl: Add "*" shorthand to set minimum io_alloc CBM for all domains

Hi Babu, Tony, Reinette,

This series was rebased on linus/master since commit 187d0801404f (tag
v6.18-12991-g187d0801404f).

As previously discussed [1], a special domain ID selector "*" has been
introduced for io_alloc_cbm that allows setting the CBM of each cache
domain to its minimum number of consecutive bits in a single operation. For
example, writing "*=0" to /sys/fs/resctrl/info/L3/io_alloc_cbm programs
each domain's CBM to the hardware-defined minimum, greatly simplifying
automation and management tasks. The user is required to specify the
correct minimum stored in /sys/fs/resctrl/info/L3/min_cbm_bits.

Please let me know your thoughts.

[1]: https://lore.kernel.org/lkml/7e117908-41ae-4f42-8863-1361101c33ab@amd.com/


Changes since v1 [2]:

 - Updated each helper for consistency (Babu Moger)
 - Refactored the loop logic in function resctrl_io_alloc_parse_line()
   to improve readability
 - Added inline keyword to each helper
 - Added inline keyword to function parse_domain_cbm()

[2]: https://lore.kernel.org/lkml/20251126171653.1004321-1-atomlin@atomlin.com/

Aaron Tomlin (3):
  fs/resctrl: Add helpers to check io_alloc support and enabled state
  fs/resctrl: Return -EINVAL for a missing seq_show implementation
  x86/resctrl: Add "*" shorthand to set minimum io_alloc CBM for all
    domains

 Documentation/filesystems/resctrl.rst     |  10 +
 arch/x86/kernel/cpu/resctrl/core.c        |   2 +-
 arch/x86/kernel/cpu/resctrl/ctrlmondata.c |  23 ++-
 fs/resctrl/ctrlmondata.c                  | 215 ++++++++++++++++------
 fs/resctrl/internal.h                     |  13 ++
 fs/resctrl/rdtgroup.c                     |   5 +-
 include/linux/resctrl.h                   |  30 ++-
 7 files changed, 230 insertions(+), 68 deletions(-)

-- 
2.51.0