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Received: from 30.74.144.121(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X138zqv_1776223535 cluster:ay36) by smtp.aliyun-inc.com; Wed, 15 Apr 2026 11:25:37 +0800 Message-ID: Date: Wed, 15 Apr 2026 11:25:35 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 10/14] mm/mglru: simplify and improve dirty writeback handling To: kasong@tencent.com, linux-mm@kvack.org Cc: Andrew Morton , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Barry Song , David Stevens , Chen Ridong , Leno Hou , Yafang Shao , Yu Zhao , Zicheng Wang , Kalesh Singh , Suren Baghdasaryan , Chris Li , Vernon Yang , linux-kernel@vger.kernel.org, Qi Zheng References: <20260413-mglru-reclaim-v5-0-8eaeacbddc44@tencent.com> <20260413-mglru-reclaim-v5-10-8eaeacbddc44@tencent.com> From: Baolin Wang In-Reply-To: <20260413-mglru-reclaim-v5-10-8eaeacbddc44@tencent.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0A306C0006 X-Stat-Signature: 1izhiutn98sj46xak3cpfmkd6npmdfdw X-HE-Tag: 1776223540-527737 X-HE-Meta: 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 NpwmNon1 i61khpCxQaE290nBlolG++GsVUaJOnfggt1/J3jwMynSapCjEe40wN+oc2TuKnBGqA7H6bQt22JtqoInm4MnKlx9rdOempKX46jZguOK6NpTIDXc70OR0stTGZRJhQ002/CN7ynNWrFCZtmB/+ap7DTCFSWy0hDLklTWK7mveiz3McwIbBAGkwL11qyebLXTy5eXt+5sCEQPpeZDgkHPebzZXBq/NT9U2oyi3NEFHGXc3xa+GqVmr+d6OgFl+A7JB+NPmI8YrF4dY1uytgR0SSk3FSqIJQKwxxGqRWO/OKZls7e/lxl5GKwU60DNc1bN0nPRdvU79j6duJoP9t5MHzHZuaK9cHfeY0tJxjDK0PulkFFBIxpPgffkd5uJiDCxKq1fDx+Q5g2lFehzIUQ0Y9RWyFIJQbr6WSBW4N6I6Yor1M2s= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/13/26 12:48 AM, Kairui Song via B4 Relay wrote: > From: Kairui Song > > Right now the flusher wakeup mechanism for MGLRU is less responsive > and unlikely to trigger compared to classical LRU. The classical > LRU wakes the flusher if one batch of folios passed to shrink_folio_list > is unevictable due to under writeback. MGLRU instead check and handle > this after the whole reclaim loop is done. > > We previously even saw OOM problems due to passive flusher, which were > fixed but still not perfect [1]. > > We have just unified the dirty folio counting and activation routine, > now just move the dirty flush into the loop right after shrink_folio_list. > This improves the performance a lot for workloads involving heavy > writeback and prepares for throttling too. > > Test with YCSB workloadb showed a major performance improvement: > > Before this series: > Throughput(ops/sec): 62485.02962831822 > AverageLatency(us): 500.9746963330107 > pgpgin 159347462 > workingset_refault_file 34522071 > > After this commit: > Throughput(ops/sec): 80857.08510208207 > AverageLatency(us): 386.653262968934 > pgpgin 112233121 > workingset_refault_file 19516246 > > The performance is a lot better with significantly lower refault. We also > observed similar or higher performance gain for other real-world workloads. > > We were concerned that the dirty flush could cause more wear for SSD: > that should not be the problem here, since the wakeup condition is when > the dirty folios have been pushed to the tail of LRU, which indicates > that memory pressure is so high that writeback is blocking the workload > already. > > Reviewed-by: Axel Rasmussen > Link: https://lore.kernel.org/linux-mm/20241026115714.1437435-1-jingxiangzeng.cas@gmail.com/ [1] > Signed-off-by: Kairui Song > --- Thanks. Makes more sense to me. I also did some testing, and seems to work well. Reviewed-by: Baolin Wang