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From: Tony Luck <tony.luck@intel.com>
To: Fenghua Yu <fenghuay@nvidia.com>,
	Reinette Chatre <reinette.chatre@intel.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>,
	Peter Newman <peternewman@google.com>,
	James Morse <james.morse@arm.com>,
	Babu Moger <babu.moger@amd.com>,
	Drew Fustini <dfustini@baylibre.com>,
	Dave Martin <Dave.Martin@arm.com>, Chen Yu <yu.c.chen@intel.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	patches@lists.linux.dev, Tony Luck <tony.luck@intel.com>
Subject: [RFC PATCH v2 11/11] fs/resctrl: Document asymmetric L2 allocation options
Date: Tue,  3 Nov 2026 13:22:54 -0800	[thread overview]
Message-ID: <20261103212254.18314-12-tony.luck@intel.com> (raw)
In-Reply-To: <20261103212254.18314-1-tony.luck@intel.com>

The rdt= kernel parameter accepts separate options for asymmetric L2 CAT and
CDP. On asymmetric systems, info/L2/cbm_mask represents the minimum cache
bitmask across domains.

Document the l2cat_asym and l2cdp_asym options and clarify the meaning of
cbm_mask.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 3 ++-
 Documentation/filesystems/resctrl.rst           | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0b3c140babd9..a16f84bed8f9 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6460,7 +6460,8 @@ Kernel parameters
 	rdt=		[HW,X86,RDT]
 			Turn on/off individual RDT features. List is:
 			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
-			mba, smba, bmec, abmc, sdciae, energy[:guid],
+			l2cat_asym, l2cdp_asym, mba, smba, bmec, abmc, sdciae,
+			energy[:guid],
 			perf[:guid].
 			E.g. to turn on cmt and turn off mba use:
 				rdt=cmt,!mba
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 524ad062a6d9..241461e0612b 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -91,6 +91,9 @@ related to allocation:
 "cbm_mask":
 		The bitmask which is valid for this resource.
 		This mask is equivalent to 100%.
+		On systems that support asymmetric, per-domain,
+		cache allocation bitmasks this is the minimum
+		mask across all domains.
 "min_cbm_bits":
 		The minimum number of consecutive bits which
 		must be set when writing a mask.
-- 
2.56.0


      parent reply	other threads:[~2026-11-03 21:23 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-03 21:22 [RFC PATCH v2 00/11] x86/resctrl: Support asymmetric L2 CAT on hybrid CPUs Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 01/11] fs/resctrl: Change UI of "max" file (merge back into earlier patches) Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 02/11] x86/resctrl: Disable symmetric L2 CAT on Panther Lake Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 03/11] x86/cpuid: Define Intel RDT enumeration leaves Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 04/11] x86/resctrl: Add asymmetric L2 CAT feature bits and boot options Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 05/11] x86/resctrl: Handle cache allocation setup failures Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 06/11] x86/resctrl: Pass the CPUID leaf to rdt_get_cache_alloc_cfg() Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 07/11] arm,x86,fs/resctrl: Store cache bitmask length per control domain Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 08/11] x86/resctrl: Use cpu_feature_enabled() for RDT allocation Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 09/11] x86/resctrl: Accept asymmetric RDT allocation features Tony Luck
2026-11-03 21:22 ` [RFC PATCH v2 10/11] x86/resctrl: Enable asymmetric CAT from CPUID leaf 0x28 Tony Luck
2026-11-03 21:22 ` Tony Luck [this message]

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