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charset=UTF-8 Content-Transfer-Encoding: 8bit X-CM-TRANSID:Syh0CgBHYH_Gq0BpmudUAQ--.49701S2 X-Coremail-Antispam: 1UD129KBjvJXoW7uF4UCFWfJFWkAryUGry7GFg_yoW8urWDpF Wvka48Ka1fJry7Jrs2y3WUZayY9ayxAw4UAr43GryxA3s8ZryFgr4Iqa15uF4kCr48Wr1a qr1q93ZxXFs8AFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUv0b4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxkF7I0En4kS 14v26r4a6rW5MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I 8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWr XwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x 0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU0 s2-5UUUUU== X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ X-Rspamd-Server: rspam02 X-Stat-Signature: 9m5gxkzm6cnpy88pempuyc7yfajr1t6a X-Rspam-User: X-Rspamd-Queue-Id: 5B3491C000E X-HE-Tag: 1765845964-431165 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/12/16 0:18, Michal Koutný wrote: > Hi. > > On Tue, Dec 09, 2025 at 01:25:52AM +0000, Chen Ridong wrote: >> From: Chen Ridong >> >> The memcg LRU was introduced to improve scalability in global reclaim, >> but its implementation has grown complex and can cause performance >> regressions when creating many memory cgroups [1]. >> >> This series implements mem_cgroup_iter with a reclaim cookie in >> shrink_many() for global reclaim, following the pattern already used in >> shrink_node_memcgs(), an approach suggested by Johannes [1]. The new >> design maintains good fairness across cgroups by preserving iteration >> state between reclaim passes. >> >> Testing was performed using the original stress test from Yu Zhao [2] on a >> 1 TB, 4-node NUMA system. The results show: > > (I think the cover letter somehow lost the targets of [1],[2]. I assume > I could retrieve those from patch 1/5.) > Hi Michal, Thanks for the reminder—I appreciate you pointing that out. Apologies for missing the links in the cover letter. You can find them in patch 1/5. > >> >> pgsteal: >> memcg LRU memcg iter >> stddev(pgsteal) / mean(pgsteal) 106.03% 93.20% >> sum(pgsteal) / sum(requested) 98.10% 99.28% >> >> workingset_refault_anon: >> memcg LRU memcg iter >> stddev(refault) / mean(refault) 193.97% 134.67% >> sum(refault) 1,963,229 2,027,567 >> >> The new implementation shows clear fairness improvements, reducing the >> standard deviation relative to the mean by 12.8 percentage points for >> pgsteal and bringing the pgsteal ratio closer to 100%. Refault counts >> increased by 3.2% (from 1,963,229 to 2,027,567). > > Just as a quick clarification -- this isn't supposed to affect regular > (CONFIG_LRU_GEN_ENABLED=n) reclaim, correct? > > Thanks, > Michal That's correct. To be precise, it only affects root reclaim when lru_gen_enabled() returns true. Note that the generation LRU can still be enabled via /sys/kernel/mm/lru_gen/enabled even when CONFIG_LRU_GEN_ENABLED=n. -- Best regards, Ridong