From patchwork Tue Mar 22 21:49:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12789294 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74A54C433EF for ; Tue, 22 Mar 2022 21:49:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0787F6B020A; Tue, 22 Mar 2022 17:49:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 028916B020B; Tue, 22 Mar 2022 17:49:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E32F86B020C; Tue, 22 Mar 2022 17:49:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0089.hostedemail.com [216.40.44.89]) by kanga.kvack.org (Postfix) with ESMTP id D482E6B020A for ; Tue, 22 Mar 2022 17:49:21 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 967E11809B0BB for ; Tue, 22 Mar 2022 21:49:21 +0000 (UTC) X-FDA: 79273363722.25.BA96488 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf26.hostedemail.com (Postfix) with ESMTP id D97BF14003A for ; Tue, 22 Mar 2022 21:49:20 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 255E5CE1E03; Tue, 22 Mar 2022 21:49:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BAA9C340EE; Tue, 22 Mar 2022 21:49:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985756; bh=ZPovejT+mS4ShXN/nfO853TOrgfFMjd8KIsrmY37H88=; h=Date:To:From:In-Reply-To:Subject:From; b=VQ+FPq88EYuoYlE4CD6Gb4EagG+YE9N176cXUfB1eWQrJJP+2z/Pk+JqnUqov6ReR nFIt7jrfF/WlWPA1hPlnITFGn8WxXhmrkAlOHGVuEX/xKsXCXfnDof9eS0CutGwUUr G5YEZswwJevnFuBv6345j6oMKgVjI4SC2PMdAmEg= Date: Tue, 22 Mar 2022 14:49:15 -0700 To: corbet@lwn.net,sj@kernel.org,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 212/227] Docs/vm/damon/design: update DAMON-Idle Page Tracking interference handling Message-Id: <20220322214916.5BAA9C340EE@smtp.kernel.org> X-Stat-Signature: po5kgkpnne7uxcfswihukpbmw6xb3wta Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=VQ+FPq88; spf=pass (imf26.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D97BF14003A X-HE-Tag: 1647985760-168234 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000062, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: SeongJae Park Subject: Docs/vm/damon/design: update DAMON-Idle Page Tracking interference handling In DAMON's early development stage before it be merged in the mainline, it was first designed to work exclusively with Idle page tracking to avoid any interference between each other. Later, but still before be merged in the mainline, because Idle page tracking is fully under the control of sysadmins, we made the resolving of conflict as the responsibility of sysadmins. The document is not updated for the change, though. This commit updates the document for that. Link: https://lkml.kernel.org/r/20220222170100.17068-3-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Signed-off-by: Andrew Morton --- Documentation/vm/damon/design.rst | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/Documentation/vm/damon/design.rst~docs-vm-damon-design-update-damon-idle-page-tracking-interference-handling +++ a/Documentation/vm/damon/design.rst @@ -84,9 +84,10 @@ table having a mapping to the address. and clear the bit(s) for next sampling target address and checks whether the bit(s) set again after one sampling period. This could disturb other kernel subsystems using the Accessed bits, namely Idle page tracking and the reclaim -logic. To avoid such disturbances, DAMON makes it mutually exclusive with Idle -page tracking and uses ``PG_idle`` and ``PG_young`` page flags to solve the -conflict with the reclaim logic, as Idle page tracking does. +logic. DAMON does nothing to avoid disturbing Idle page tracking, so handling +the interference is the responsibility of sysadmins. However, it solves the +conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags, +as Idle page tracking does. Address Space Independent Core Mechanisms