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Thu, 12 Feb 2026 13:25:28 -0800 (PST) Message-ID: Date: Thu, 12 Feb 2026 13:25:26 -0800 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/mempolicy: track page allocations per mempolicy To: Vlastimil Babka , linux-mm@kvack.org Cc: apopple@nvidia.com, akpm@linux-foundation.org, 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, mhocko@suse.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, ying.huang@linux.alibaba.com, yuanchu@google.com, ziy@nvidia.com, kernel-team@meta.com References: <20260212045109.255391-1-inwardvessel@gmail.com> <20260212045109.255391-2-inwardvessel@gmail.com> <96b63efb-551f-4dd5-b4a2-ac67da577431@suse.cz> Content-Language: en-US From: JP Kobryn In-Reply-To: <96b63efb-551f-4dd5-b4a2-ac67da577431@suse.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/12/26 7:24 AM, Vlastimil Babka wrote: > On 2/12/26 05:51, JP Kobryn wrote: >> It would be useful to see a breakdown of allocations to understand which >> NUMA policies are driving them. For example, when investigating memory >> pressure, having policy-specific counts could show that allocations were >> bound to the affected node (via MPOL_BIND). >> >> Add per-policy page allocation counters as new node stat items. These >> counters can provide correlation between a mempolicy and pressure on a >> given node. >> >> Signed-off-by: JP Kobryn >> Suggested-by: Johannes Weiner > > Are the numa_{hit,miss,etc.} counters insufficient? Could they be extended > in a way that would capture any missing important details? A counter per > policy type seems exhaustive, but then on one hand it might be not important > to distinguish beetween some of them, and on the other hand it doesn't track > the nodemask anyway. The two patches of the series should complement each other. When investigating memory pressure, we could identify the affected nodes (patch 2). Then we can cross-reference the policy-specific stats to find any correlation (this patch). I think extending numa_* counters would call for more permutations to account for the numa stat per policy. I think distinguishing between MPOL_DEFAULT and MPOL_BIND is meaningful, for example. Am I understanding your question?