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Thu, 17 Sep 2026 15:37:47 +0000 Message-ID: <8230dae2-2cb0-4b46-8cec-dc4e281d4e4a@intel.com> Date: Thu, 17 Sep 2026 08:37:43 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/5] riscv_cbqri: resctrl: Add cache allocation via capacity block mask To: Drew Fustini , Adrien Ricciardi , Alexandre Ghiti , Atish Kumar Patra , Atish Patra , Babu Moger , Ben Horgan , Borislav Petkov , Chen Pei , Conor Dooley , Conor Dooley , Dave Hansen , Dave Martin , Fenghua Yu , Gong Shuai , Gong Shuai , , James Morse , =?UTF-8?Q?Kornel_Dul=C4=99ba?= , Krzysztof Kozlowski , , "Liu Zhiwei" , Palmer Dabbelt , Paul Walmsley , Peter Newman , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Rob Herring , Samuel Holland , "Sebastian Andrzej Siewior" , Tony Luck , Vasudevan Srinivasan , Ved Shanbhogue , Weiwei Li , yunhui cui , Zhanpeng Zhang CC: , , , , , References: <20260901-dfustini-atl-sc-cbqri-dt-v7-0-ca2935d85622@kernel.org> <20260901-dfustini-atl-sc-cbqri-dt-v7-2-ca2935d85622@kernel.org> From: Reinette Chatre Content-Language: en-US In-Reply-To: <20260901-dfustini-atl-sc-cbqri-dt-v7-2-ca2935d85622@kernel.org> Content-Type: text/plain; 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A level > whose controllers disagree is left unexposed. Other levels are > unaffected. If I understand correctly, while attempting to translate to resctrl terms, this means that a cache resource with several domains may support different capacity masks in the domains? I believe the "single cap set per rid" you refer to is /sys/fs/resctrl/info/L3/cbm_mask and /sys/fs/resctrl/info/L2/cbm_mask that exposes a single capacity bitmask representing the maximum allocation. As you know, resctrl is in the process of changing the way in which schema formats are described. The most recent PoC [1] added new bitmap description files but it kept a single value "max" file to describe the highest allocation possible for a bitmap schema. To support asymmetrical cache instances it looks like changing the interface to describe the maximum per domain (instead of one global value) could address the gap? For example, if there is a hypothetical system with two L2 cache instances, one with a 0xFF max CBM and the other with a 0XF max CBM then resctrl could expose it as: # cat /sys/fs/resctrl/info/L2/schemata/L2/max 0=ff;1=f The schemata file currently and will continue to display the allocations per domain. resctrl will need more changes to support different CBM per domain internally and until then all these CBMs will be the same, but adding this change to user interface now may set resctrl up to support these systems in the future? Reinette [1] https://lore.kernel.org/lkml/d258a32f-12d5-464d-abe9-4720fb3e44b3@intel.com/