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b=t7Zex76sZygL34C3bGAE/bdKfCXA/NQNhzNyXl5a34bLDu8qnEAUmyJW3fxNhw08C tbzAmjUEM+gttOp+naQ4mxx1OuMWy2NNsfLeeotgwWGP1gKVbMKuceyohlZcWvq/Bc fthpJqRPvByozPwnLn76K5SqpPFTRbAOt0lo2jro= Date: Tue, 27 Oct 2026 19:24:14 -0700 From: Andrew Morton To: Joanne Koong Cc: Shakeel Butt , Yosry Ahmed , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 0/2] memcg: reduce cacheline contention from lruvec stat Message-Id: <20261027192414.cb3318abc07232ec5f1bc937@linux-foundation.org> In-Reply-To: References: <20261023195417.1391216-1-joannelkoong@gmail.com> <20261023155407.0b519a3da7313137a0276119@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) X-Archived-By: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: CE676140006 X-Stat-Signature: 5ib6atmoqkrntmexzaiib4reu4678wdc X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793154256-864900 X-HE-Meta: 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 EPzKgAgr 2pW724n9lzF+0U2xwfLEYs75PKXQDgfdCdyGMN6hmVAMNbewN38ozcCwgf0J3S7LmpdXn6F7BiSd4DbHHM8oK5eAO6GVJwJMNwTf7coL1KJO3rwvzyY516GjeEUIgSTT3gEEao0nt8KmL5feV9flRZc3Zz7iu0GSgt5NMq9Co9GHVFJyC68E7OtnCV5zgzGjbqoIKxE2f9IeBpwYV/KUR33Q6mGgTQ4FwDUPsCy1r44I6fSsIPJaAJdN28tueez8ZXqITaZut/v0xdDFyTmtyAoxO5g== 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 Tue, 27 Oct 2026 15:57:43 -0700 Joanne Koong wrote: > Here's an updated version of the "Fix this by moving the memcg_pn_cold > group..." paragraph in patch 1 that mentions this: > > Fix this by moving the memcg_pn_cold group, which is only touched when > the memcg is reparented or freed, right after memcg_pn_read_mostly. > SLAB_HWCACHE_ALIGN only aligns objects to a cacheline, and the struct > is 576 bytes, so depending on where an object lands, its read-mostly > cacheline is now paired either with its cold cacheline or with the last > cacheline of the preceding object, which holds the end of > lru_zone_size[] and the reclaim iterator. Both are rarely written > outside of reclaim, so either way the read-mostly cacheline is no > longer paired with the LRU list heads. > > Would you be able to swap it in or would you prefer that I send a v4? Thanks. I'll take care of this when I process the patchset. Which will be quite soon now we're all merged up.