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Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0X.9ya0W_1773729894 cluster:ay36) by smtp.aliyun-inc.com; Tue, 17 Mar 2026 14:45:07 +0800 From: "Huang, Ying" To: "JP Kobryn (Meta)" Cc: "Vlastimil Babka (SUSE)" , linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com, apopple@nvidia.com, axelrasmussen@google.com, byungchul@sk.com, cgroups@vger.kernel.org, david@kernel.org, eperezma@redhat.com, gourry@gourry.net, jasowang@redhat.com, hannes@cmpxchg.org, joshua.hahnjy@gmail.com, Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, mst@redhat.com, rppt@kernel.org, muchun.song@linux.dev, zhengqi.arch@bytedance.com, rakie.kim@sk.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, surenb@google.com, virtualization@lists.linux.dev, weixugc@google.com, xuanzhuo@linux.alibaba.com, yuanchu@google.com, ziy@nvidia.com, kernel-team@meta.com Subject: Re: [PATCH v2] mm/mempolicy: track page allocations per mempolicy In-Reply-To: <0d66401f-9874-4047-971b-632723b0b7ee@linux.dev> (JP Kobryn's message of "Mon, 16 Mar 2026 21:37:01 -0700") References: <20260307045520.247998-1-jp.kobryn@linux.dev> <3a42463b-9ddd-4d64-b64c-6c2e6e4fc75d@kernel.org> <343bbd5b-67a0-46c4-8ec4-69158bf26b3f@linux.dev> <874imkpba1.fsf@DESKTOP-5N7EMDA> <60f71f4c-71d9-4751-8c6b-10179b98bef0@kernel.org> <87sea0o55p.fsf@DESKTOP-5N7EMDA> <0d66401f-9874-4047-971b-632723b0b7ee@linux.dev> Date: Tue, 17 Mar 2026 14:44:59 +0800 Message-ID: <87a4w7x8d0.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: 7D0538000B X-Rspamd-Server: rspam07 X-Stat-Signature: 9ayu3rt5z4w7icfzfde63m41kciy7qxp X-Rspam-User: X-HE-Tag: 1773729915-916235 X-HE-Meta: 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 mxVauWHz Ok3byyfDS/Zovnev0QiMv/8TVru5q953pog1LJV4qotRR7jqwMC9lYC0SvRq5bI92Z4OzryB91JvWopo5I+hOwUPPsATqM2HNLqeeJ51yMi1AxgCmBK9DAyI33jFxT5UuRY6AO8+AZcocS4pcA9i/7b0aMQF5nzlrYKYWKKMAaWjQV4aCZ6L+jua/XmaFC10F8NLM4vQ25o7RYNoAfWUf4G60YDv9yc7H5s6Xj/jcQI0wCqgO3MzKz61ZMRIvK7YxwnUU/7owMgTFgdVIHmGmqdPfgIqlltUG2wInS0fHz9fwAy/nEBzI1d6vwe8Ponz6Ep5lTCp9c1MURxX4/DWDbARqhw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: "JP Kobryn (Meta)" writes: > On 3/15/26 7:54 PM, Huang, Ying wrote: >> "JP Kobryn (Meta)" writes: >> >>> On 3/13/26 12:34 AM, Vlastimil Babka (SUSE) wrote: >>>> On 3/13/26 07:14, JP Kobryn (Meta) wrote: >>>>> On 3/12/26 10:07 PM, Huang, Ying wrote: >>>>>> "JP Kobryn (Meta)" writes: >>>>>> >>>>>>> On 3/12/26 6:40 AM, Vlastimil Babka (SUSE) wrote: >>>>>>> >>>>>>> How about I change from per-policy hit/miss/foreign triplets to a single >>>>>>> aggregated policy triplet (i.e. just 3 new counters which account for >>>>>>> all policies)? They would follow the same hit/miss/foreign semantics >>>>>>> already proposed (visible in quoted text above). This would still >>>>>>> provide the otherwise missing signal of whether policy-driven >>>>>>> allocations to a node are intentional or fallback. >>>>>>> >>>>>>> Note that I am also planning on moving the stats off of the memcg so the >>>>>>> 3 new counters will be global per-node in response to similar feedback. >>>>>> >>>>>> Emm, what's the difference between these newly added counters and the >>>>>> existing numa_hit/miss/foreign counters? >>>>> >>>>> The existing counters don't account for node masks in the policies that >>>>> make use of them. An allocation can land on a node in the mask and still >>>>> be considered a miss because it wasn't the preferred node. >>>> That sounds like we could just a new counter e.g. numa_hit_preferred >>>> and >>>> adjust definitions accordingly? Or some other variant that fills the gap? >>> >>> It's an interesting thought. Looking into these existing counters more, >>> the in-kernel direct node allocations, which don't fall under any >>> mempolicy, are also included in these stats. One good example might be >>> include/linux/skbuff.h, where __dev_alloc_pages() calls >>> alloc_pages_node_noprof(NUMA_NO_NODE, ...) which eventually reaches >>> zone_statistics() and increments the stats. >> IIUC, the default memory policy is used here, that is, MPOL_LOCAL. > > I'm not seeing that. zone_statistics() is eventually reached. > alloc_pages_mpol() is not. Yes. The page isn't allocated through alloc_pages_mpol(). For example, if we want to allocate pages for the kernel instead of user space applications. However, IMHO, the equivalent memory policy is MPOL_LOCAL, that is, allocate from local node firstly, then fallback to other nodes. I don't think that alloc_pages_mpol() is so special. --- Best Regards, Huang, Ying