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 D27E7C4332F for ; Mon, 13 Nov 2023 13:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231480AbjKMNBp (ORCPT ); Mon, 13 Nov 2023 08:01:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231261AbjKMNBZ (ORCPT ); Mon, 13 Nov 2023 08:01:25 -0500 Received: from out30-112.freemail.mail.aliyun.com (out30-112.freemail.mail.aliyun.com [115.124.30.112]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A31E42129 for ; Mon, 13 Nov 2023 05:01:14 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R331e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0VwL5nxU_1699880472; Received: from 30.97.48.50(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VwL5nxU_1699880472) by smtp.aliyun-inc.com; Mon, 13 Nov 2023 21:01:12 +0800 Message-ID: Date: Mon, 13 Nov 2023 21:01:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm: support large folio numa balancing To: Kefeng Wang , David Hildenbrand , akpm@linux-foundation.org Cc: ying.huang@intel.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, John Hubbard References: <606d2d7a-d937-4ffe-a6f2-dfe3ae5a0c91@redhat.com> <70973a55-63a0-4a85-abe5-d8681fdb3886@huawei.com> From: Baolin Wang In-Reply-To: <70973a55-63a0-4a85-abe5-d8681fdb3886@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/13/2023 8:10 PM, Kefeng Wang wrote: > > > On 2023/11/13 18:53, David Hildenbrand wrote: >> On 13.11.23 11:45, Baolin Wang wrote: >>> Currently, the file pages already support large folio, and supporting >>> for >>> anonymous pages is also under discussion[1]. Moreover, the numa >>> balancing >>> code are converted to use a folio by previous thread[2], and the >>> migrate_pages >>> function also already supports the large folio migration. >>> >>> So now I did not see any reason to continue restricting NUMA >>> balancing for >>> large folio. >> >> I recall John wanted to look into that. CCing him. >> >> I'll note that the "head page mapcount" heuristic to detect sharers will >> now strike on the PTE path and make us believe that a large folios is >> exclusive, although it isn't. >> >> As spelled out in the commit you are referencing: >> >> commit 6695cf68b15c215d33b8add64c33e01e3cbe236c >> Author: Kefeng Wang >> Date:   Thu Sep 21 15:44:14 2023 +0800 >> >>      mm: memory: use a folio in do_numa_page() >>      Numa balancing only try to migrate non-compound page in >> do_numa_page(), >>      use a folio in it to save several compound_head calls, note we use >>      folio_estimated_sharers(), it is enough to check the folio >> sharers since >>      only normal page is handled, if large folio numa balancing is >> supported, a >>      precise folio sharers check would be used, no functional change >> intended. >> >> >> I'll send WIP patches for one approach that can improve the situation >> soonish. > > When convert numa balance to use folio, I make similar change, it works > with large anon folio(test with v5), but David's precise folio sharers > should be merged firstly, also if a large folio shared by many process, > we maybe split it, don't sure about it, this need some evaluation. IIUC, numa balancing will not split the large folio.