From patchwork Thu Mar 20 18:04:39 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Shiju Jose X-Patchwork-Id: 14024317 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11808227B83; Thu, 20 Mar 2025 18:05:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742493938; cv=none; b=Z4cs60hyWNSVBazxxZ4WkJy4frEzMAFAeZVUgCZ5LvXPjY9+7OWZHtS7dw+qWmy6yrnXX8XkIqwFLjYVV4n1BRglvaqxMexqoe2aaOjUrXhYzehlWeMYxc+NV/Ibk6nSLUvPbyzA9wyHbHs6ZsQCectQ1rPAFbLRo02DErE9M3A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742493938; c=relaxed/simple; bh=SD+DdQiarUAS24vNkjCi+X85etZk11V+cPYKINi+TOE=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=vFGwKJ/dZTECKgGXe/SFfaa+NQEevFKHsVY14xqMcyFV8Eyio8o7M77L8GFs21EiXQXIJrBUuhNCL4A/SFp2ukY0dQx9xTIhWaonSLQEnrCRawGlWmUJVgbGD3Qy/BQby7ztGg9AeUgIGHHCqwSewtlTApNJco1jDIqMrxi2UtQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4ZJYK32CMbz6L58c; Fri, 21 Mar 2025 02:00:39 +0800 (CST) Received: from frapeml500007.china.huawei.com (unknown [7.182.85.172]) by mail.maildlp.com (Postfix) with ESMTPS id CBD7314050D; 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> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: lhrpeml100003.china.huawei.com (7.191.160.210) To frapeml500007.china.huawei.com (7.182.85.172) 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`