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Received: from 30.74.144.136(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XEUXxmG_1794298201 cluster:ay36) by smtp.aliyun-inc.com; Tue, 10 Nov 2026 16:10:02 +0800 Message-ID: Date: Tue, 10 Nov 2026 16:10:00 +0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/4] mm/huge_memory: add a per-order counter for underused splits To: Joanne Koong , akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: baohua@kernel.org, usama.arif@linux.dev, hannes@cmpxchg.org, kas@kernel.org, alex@ghiti.fr, ziy@nvidia.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, willy@infradead.org, linux-mm@kvack.org References: <20261103212004.1356327-1-joannelkoong@gmail.com> <20261103212004.1356327-4-joannelkoong@gmail.com> From: Baolin Wang In-Reply-To: <20261103212004.1356327-4-joannelkoong@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 5yyo9jw4hkyakdspk9go9rd91axjz6g6 X-Rspamd-Server: rspam01 X-Rspam-User: X-Spam-Status: No, score=-19.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: C253140008 X-HE-Tag: 1794298206-700366 X-HE-Meta: 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 L0vhu5uq WIes+QpxAYw5bFSwnt8At0jth7+x79NCwjpZQsyaoRhdNatWQMNxaXlz1yn6wKNQk8i8NpyCvJxD/zn0eYdnbnuoyGBZrmW3bBYKNESUz9w0E+9PNqa+9txKOahVzY2JBPvpLjkxhNHWeEtWgB4syXxAecHbh6BiYoIUuGrESVLU9t1red2gjaTMI1u8s6uOQpDk2IUynJJR+cN8+sNZwGoIw/v/KRE8sYyh87nZck2loOsgLFRRY5BtLs/4SiLGKhne5xLdKNGqH5j3XCvNGFAoc3onA/GVa+/9Kp/y3Y92WyKpaKdVKuf7NG16JjYdqFDKpeGZAXEUrsoQeaD97LPvfFwvzPPmvdgEes9dlNv13pG2/Ibrg9JjZ2fTckrlwssz86X/NPgOYuuQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/4/26 5:20 AM, Joanne Koong wrote: > thp_underused_split_page counts every folio that the deferred split > shrinker splits for being underused. Today that is only ever a > PMD-sized folio, but a later patch queues anonymous mTHP folios for > underused splitting too, at which point this counter would start > counting mTHP splits as well. > > thp_underused_split_page could then end up larger than thp_split_page, > and there would be no per-order count of underused splits. That doesn't > match how the other THP split stats work. In /proc/vmstat, > thp_split_page and thp_deferred_split_page only count PMD-sized folios. > Splits of every size, PMD included, are counted per order in the split > and split_deferred stats under hugepages-/stats/. > > Do the same for underused splits. Only count PMD-sized folios in > thp_underused_split_page, and add a per-order split_underused stat that > counts underused splits of every size. The folio's order has to be read > before splitting it, since the folio is no longer large once the split > succeeds. > > There is no functional change to thp_underused_split_page yet, as only > PMD-sized folios are split for being underused today. > > Suggested-by: Kiryl Shutsemau > Signed-off-by: Joanne Koong > --- LGTM. Reviewed-by: Baolin Wang