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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EE6DC433FE for ; Wed, 18 May 2022 19:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242093AbiERTvR (ORCPT ); Wed, 18 May 2022 15:51:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231796AbiERTvP (ORCPT ); Wed, 18 May 2022 15:51:15 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78825A444; Wed, 18 May 2022 12:51:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652903473; x=1684439473; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=qI2hRvQWGqLlvCgm5r1r2wIsZFcii9ZgTyxajRKplqk=; b=HnF17rcebY7JhrTHtbMkV9gZnCRCyOeotFWbV5UC1PS6FO46q9AjRe0E ARodhDmCNdA5Ukt8xz95d6R9qcZPBK6Uedg7eoWuNywTnG/TdhJjpTADH XzomDAaau/qzQPMhtbIwwW+xgGYgQJ+WjcJQGDp7GCHovG5D3P5TPGpFO mJSEE80YzLz3ZNDtAN4EUIIfzR0vcRUGCS++qiBOLtFOYV2yuqULXI9R+ 0vcwOQW+iVJqB35YCmg+nAp2eNVptCfTe4+RQnHciFPPJ5sIkeEbzU1n4 xDKoMyVTkge5FNb6uHZiZG+bM7t9LGXJqp+uSdGQnABoFHqHtCuCe0aRt g==; X-IronPort-AV: E=McAfee;i="6400,9594,10351"; a="253913619" X-IronPort-AV: E=Sophos;i="5.91,235,1647327600"; d="scan'208";a="253913619" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2022 12:51:13 -0700 X-IronPort-AV: E=Sophos;i="5.91,235,1647327600"; d="scan'208";a="817618883" Received: from kackerma-mobl2.amr.corp.intel.com (HELO [10.209.69.102]) ([10.209.69.102]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2022 12:51:11 -0700 Message-ID: Date: Wed, 18 May 2022 12:51:10 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH] Revert "mm/vmscan: never demote for memcg reclaim" Content-Language: en-US To: Johannes Weiner , Dave Hansen , "Huang, Ying" , Yang Shi , Andrew Morton Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Zi Yan , Michal Hocko , Shakeel Butt , Roman Gushchin References: <20220518190911.82400-1-hannes@cmpxchg.org> From: Dave Hansen In-Reply-To: <20220518190911.82400-1-hannes@cmpxchg.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/18/22 12:09, Johannes Weiner wrote: > However, with NUMA balancing now doing tier promotions, demotion is > part of the page aging process. Global reclaim demotes the coldest > toptier pages to secondary memory, where their life continues and from > which they have a chance to get promoted back. Essentially, tiered > memory systems have an LRU order that spans multiple nodes. Thanks for the detailed explanation. Ultimately, this was just intended as an optimization to make cgroup reclaim more efficient. But, I agree that ordering correctness should trump efficiency. Acked-by: Dave Hansen