From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0B1E3DC4D0 for ; Fri, 13 Mar 2026 18:10:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773425428; cv=none; b=nqqyIHKTaJ5WYUhCqjVO/YxBvRHPsLCqZHWC+sLIaZfAQMyUnONO2CuaKaICdm2l+w7BFaOCSY0PQpsTgfMZqII/0XFyIsf3As+FirPq2aemuJtyNFu2yo9FMUvROUAkA9tlUMq7MwCyMna5gQ/aY69j0hNl9brO2AoutJ1Fk4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773425428; c=relaxed/simple; bh=1EMhY1/dh06aGZ8ai/vFAY1FUFkV1XYrfXGFePNbaVg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mKUgtmsy6Tj+dDTa/7EWZYDEq2K6g14HM91tLorJziYm9MTZzSgFNuRpbEVgDixqs1scfKs0Zzi60ZT1aAW1qx/WWr0TT4Pan6dG2u3TPhnQO6MgYDiNjhKGVwGX88s1sJJzm3m4BnrjxW2evQCxD8yQEdi+gXb4h/w+Na3sGFQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=YEvWVGE/; arc=none smtp.client-ip=95.215.58.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="YEvWVGE/" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1773425412; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xUL9iRVLMyXGemsBV+GDYxg+OBxgQpSH1wtXeqP+d0s=; b=YEvWVGE/vbF7fkuKv1vaaemG2cWn8qs3WvDY8NQ1y92/L5WaA4y8MG5AlMSRpQflNu55rL JiqeO3Gw3ND+eHIqodiU/8IaTA9IT4Ruj0jRn7q0b3QRLggJP8MAfKSlRAyVQSzvJgf6Pg vT3r6XXfYhTLynppaDvP8cT1KQr7IdU= Date: Fri, 13 Mar 2026 11:09:58 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2] mm/mempolicy: track page allocations per mempolicy To: "Vlastimil Babka (SUSE)" , "Huang, Ying" Cc: 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 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> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "JP Kobryn (Meta)" In-Reply-To: <60f71f4c-71d9-4751-8c6b-10179b98bef0@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT 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. So if we applied the hit/miss/foreign semantics in this patch to the existing counters we would be mixing allocations that are in and out of policy, losing the accuracy. The new 3 counters I last proposed (in an effort to reduce the amount of new counters as much as possible) would isolate mempolicy allocs and be named to reflect that: numa_mpol_{hit,miss,foreign}.