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Fri, 21 Mar 2025 02:05:33 +0800 (CST) Received: from P_UKIT01-A7bmah.china.huawei.com (10.48.156.145) by frapeml500007.china.huawei.com (7.182.85.172) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Thu, 20 Mar 2025 19:05:31 +0100 From: To: , , , , , , , , , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v2 2/8] EDAC: Update documentation for the CXL memory patrol scrub control feature Date: Thu, 20 Mar 2025 18:04:39 +0000 Message-ID: <20250320180450.539-3-shiju.jose@huawei.com> X-Mailer: git-send-email 2.43.0.windows.1 In-Reply-To: <20250320180450.539-1-shiju.jose@huawei.com> References: <20250320180450.539-1-shiju.jose@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.48.156.145] X-ClientProxiedBy: lhrpeml100003.china.huawei.com (7.191.160.210) To frapeml500007.china.huawei.com (7.182.85.172) X-Rspam-User: X-Rspamd-Queue-Id: B45EAA0017 X-Rspamd-Server: rspam05 X-Stat-Signature: zwr6w5bpsezme1ni37bod4sk614jzamt X-HE-Tag: 1742493936-473969 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Shiju Jose Update the Documentation/edac/scrub.rst to include descriptions and policies for CXL memory device-based and CXL region-based patrol scrub control. Note: This may require inputs from CXL memory experts regarding region-based scrubbing policies. Signed-off-by: Shiju Jose --- Documentation/edac/scrub.rst | 47 ++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/Documentation/edac/scrub.rst b/Documentation/edac/scrub.rst index daab929cdba1..d1c02bd90090 100644 --- a/Documentation/edac/scrub.rst +++ b/Documentation/edac/scrub.rst @@ -264,3 +264,51 @@ Sysfs files are documented in `Documentation/ABI/testing/sysfs-edac-scrub` `Documentation/ABI/testing/sysfs-edac-ecs` + +Examples +-------- + +The usage takes the form shown in these examples: + +1. CXL memory device patrol scrubber + +1.1 Device based scrubbing + +CXL memory is exposed to memory management subsystem and ultimately userspace +via CXL devices. + +For cases where hardware interleave controls do not directly map to regions of +Physical Address space, perhaps due to interleave the approach described in  +1.2 Region based scrubbing section, which is specific to CXL regions should be +followed. In those cases settings on the presented interface may interact with +direct control via a device instance specific interface and care must be taken. + +Sysfs files for scrubbing are documented in +`Documentation/ABI/testing/sysfs-edac-scrub` + +1.2. Region based scrubbing + +CXL memory is exposed to memory management subsystem and ultimately userspace +via CXL regions. CXL Regions represent mapped memory capacity in system +physical address space. These can incorporate one or more parts of multiple CXL +memory devices with traffic interleaved across them. The user may want to control +the scrub rate via this more abstract region instead of having to figure out the +constituent devices and program them separately. The scrub rate for each device +covers the whole device. Thus if multiple regions use parts of that device then +requests for scrubbing of other regions may result in a higher scrub rate than +requested for this specific region. + +1. When user sets scrub rate for a memory region, the scrub rate for all the CXL + memory devices interleaved under that region is updated with the same scrub + rate. + +2. When user sets scrub rate for a memory device, only the scrub rate for that + memory devices is updated though device may be part of a memory region and + does not change scrub rate of other memory devices of that memory region. + +3. Scrub rate of a CXL memory device may be set via EDAC device or region scrub + interface simultaneously. Care must be taken to prevent a race condition, or + only region-based setting may be allowed. + +Sysfs files for scrubbing are documented in +`Documentation/ABI/testing/sysfs-edac-scrub`