From mboxrd@z Thu Jan 1 00:00:00 1970 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 E4D3DC00140 for ; Mon, 1 Aug 2022 02:15:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 54E428E0002; Sun, 31 Jul 2022 22:15:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4FE218E0001; Sun, 31 Jul 2022 22:15:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3C5048E0002; Sun, 31 Jul 2022 22:15:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 2ECB68E0001 for ; Sun, 31 Jul 2022 22:15:28 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id E91EA14073C for ; Mon, 1 Aug 2022 02:15:27 +0000 (UTC) X-FDA: 79749407094.04.D79BF8A Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf02.hostedemail.com (Postfix) with ESMTP id 10CDF800E3 for ; Mon, 1 Aug 2022 02:15:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1659320127; x=1690856127; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=0dkdwZhWtVX2hh1joNPi9o16J5ddF58YnogdpW4lxAM=; b=dYL4dcdJnCY6RF7YBebaVg3boUeMrgxre/YnrXfnrM0hiC+STVkCT8ar KDx4E8y2RTIDDE6DKYcae6r+PfHqKAac4rCdkB8HqyXGNHKNudADV8bR/ ckX+lrKr+XG6WRT1GXlcFSobkFpAwjNs3j5boxBF6GfWdrMRhL9GvB+iS QL60z+MuiOesx1bfQrHzU+JKJ0fO9QbAneDVENgYMg0houcnwODV504oW XHPuP1yEW6+UkLSr7cv0MpGnzL5VrUM3C9nsJx2r41CU1vpwKe6jGr7x1 GHXRFoCrtLaPt/Hk04BQwPUWLsmDg3bWT+hZXNyoUKFimqYcXq38aUWK7 A==; X-IronPort-AV: E=McAfee;i="6400,9594,10425"; a="287803549" X-IronPort-AV: E=Sophos;i="5.93,206,1654585200"; d="scan'208";a="287803549" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2022 19:15:25 -0700 X-IronPort-AV: E=Sophos;i="5.93,206,1654585200"; d="scan'208";a="577617016" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2022 19:15:21 -0700 From: "Huang, Ying" To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, akpm@linux-foundation.org, Wei Xu , Yang Shi , Davidlohr Bueso , Tim C Chen , Michal Hocko , Linux Kernel Mailing List , Hesham Almatary , Dave Hansen , Jonathan Cameron , Alistair Popple , Dan Williams , Johannes Weiner , jvgediya.oss@gmail.com Subject: Re: [PATCH v11 5/8] mm/demotion: Build demotion targets based on explicit memory tiers References: <20220728190436.858458-1-aneesh.kumar@linux.ibm.com> <20220728190436.858458-6-aneesh.kumar@linux.ibm.com> <87wnbwl92w.fsf@yhuang6-desk2.ccr.corp.intel.com> <878rocs7ru.fsf@linux.ibm.com> Date: Mon, 01 Aug 2022 10:15:17 +0800 In-Reply-To: <878rocs7ru.fsf@linux.ibm.com> (Aneesh Kumar K. V.'s message of "Fri, 29 Jul 2022 12:52:13 +0530") Message-ID: <87fsiglney.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=dYL4dcdJ; spf=pass (imf02.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=ying.huang@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659320127; a=rsa-sha256; cv=none; b=gSTb5JCOmxDPJ+MJ/yoHvVxgzODvT8NCQul5d8q7s4j2uEjeAmyoU4dGfNORFXFyD3fcak 2/odKY2DL6jN267YdGLcqxwN9vtwm6/dQ1a+CGBnLTkt1czx9cSqMCke428GCjw2Oux8UC JU+LrQzl6WFYd/fiSxyZexISD1GrjPo= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659320127; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AEqw0vxqkwNTMRW2BRRGNA0BnBwmGqD7mILymv8OLBY=; b=J79KUnW3N2C16TaPO6dXWE/4fD7kSqF5giK7Qcv5ep8uKFSBz4xKraZuuP36W1NLVI6gqc BymSB+/q0a1mxjzKcQ5QqAUC+TBOw1YqUVlQzDAsKc4oL9X3KCHH9+Dqedjz1+rYa754sP XPMEyqd0VWpOGHXdvTKv+sFMsHuXbFk= X-Stat-Signature: 7antrrqsmxbdqsbd1zpmwzi74rjciqk8 X-Rspamd-Queue-Id: 10CDF800E3 X-Rspam-User: Authentication-Results: imf02.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=dYL4dcdJ; spf=pass (imf02.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=ying.huang@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspamd-Server: rspam04 X-HE-Tag: 1659320126-698017 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: "Aneesh Kumar K.V" writes: > "Huang, Ying" writes: > >> "Aneesh Kumar K.V" writes: >> + */ > > .... > >>> +int next_demotion_node(int node) >>> +{ >>> + struct demotion_nodes *nd; >>> + int target; >>> + >>> + if (!node_demotion) >>> + return NUMA_NO_NODE; >>> + >>> + nd = &node_demotion[node]; >>> + >>> + /* >>> + * node_demotion[] is updated without excluding this >>> + * function from running. >>> + * >>> + * Make sure to use RCU over entire code blocks if >>> + * node_demotion[] reads need to be consistent. >>> + */ >>> + rcu_read_lock(); >>> + /* >>> + * If there are multiple target nodes, just select one >>> + * target node randomly. >>> + * >>> + * In addition, we can also use round-robin to select >>> + * target node, but we should introduce another variable >>> + * for node_demotion[] to record last selected target node, >>> + * that may cause cache ping-pong due to the changing of >>> + * last target node. Or introducing per-cpu data to avoid >>> + * caching issue, which seems more complicated. So selecting >>> + * target node randomly seems better until now. >>> + */ >>> + target = node_random(&nd->preferred); >> >> Don't find code to optimize node_random() for weight == 1 case, forget >> to do that? > > I guess you suggested to do that as the patch for node_random or did I > got the review feedback wrong? Yes. > https://lore.kernel.org/linux-mm/87y1wdn30p.fsf@yhuang6-desk2.ccr.corp.intel.com > > The change for node_random will be patch outside this series. I think we can include it in this series. Because the series provide more information about why we need the change. Best Regards, Huang, Ying