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AJvYcCWRO5kMWgmNbc8qjWCTHxclpNtAYwbJ5+1UIBkejVbRF5ye+1kyqt74S582/PmXtnhQ3jLw6QdWtQ==@kvack.org X-Gm-Message-State: AOJu0Yz4dOT4RoReAlim6ZOoC/WoGs/PpfocmL7YF77P7Kqp05k8sSX7 X1r4swfiJVwIhsOWWejS5mvog3fKtXzIxNUSwtpJkKE620J18DK+moXDxujcpn8aZ00Hq8modG0 /yLS+okzO7X4iQsF4vg4DCKQkBxroxYiIWmaCifkL3tR6p1tP5UqePQ== X-Gm-Gg: ASbGncs7YNSyvG6pAdpd0pYqsnp90PXyrRN3kAhIUFhPur/aGpJwDt6VAckocnxUezE YtV1zs/y2t48AsZHS/bu6/dnL1cpZtgVOGgytBxgAS8pYkUVBbuhq3hL1SSxmkDNbJtEYwQYr1C uKVXZTHRp582uq2sGNSVLeIoSaOjGNnm1VBTTEB2bY X-Google-Smtp-Source: AGHT+IEvjYCUz8+4rdFfCSurcxSpdJL3vG3Az7HPINb1JM3PerHD1lC7Td2QRd0UxLGyaIs3gOzfVrzXmJ3QkkmoRrw= X-Received: by 2002:a05:6512:1597:b0:549:8f24:b617 with SMTP id 2adb3069b0e04-54990e2c019mr8873182e87.4.1741856574247; Thu, 13 Mar 2025 02:02:54 -0700 (PDT) MIME-Version: 1.0 References: <20250313034812.3910627-1-hezhongkun.hzk@bytedance.com> In-Reply-To: From: Zhongkun He Date: Thu, 13 Mar 2025 17:02:41 +0800 X-Gm-Features: AQ5f1JpXLeTNidzVpI0S8XFw2I56K4hTNHQkbtr22KOqanhQ0XZYUc7wNGjGRos Message-ID: Subject: Re: [External] Re: [PATCH V1] mm: vmscan: skip the file folios in proactive reclaim if swappiness is MAX To: Michal Hocko Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 7A50B1A000A X-Stat-Signature: uo6h6ah1qzikcgj6qa3p666379j19tuc X-Rspamd-Server: rspam06 X-HE-Tag: 1741856576-250526 X-HE-Meta: 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 k6Sqx0qx BHocgwUy8hV3CsGTMd+SNgPyx4QIbOSHAoUSScEwI55EpnKZfytkWk24Z/CriU55XPOrFnWPbPJkTtdU/Mmixg6vYpWeLl88amr5Vjx0VIdjKAGlhbSAcul/m3UfcSnPEe6bc6nVs7sTCgBtH2S6r306qLhedVniAWahEpFehm+RjoyMn8C5gawO7J6wCudzkSKFqs5AsqSckrjEJKcBcfFRG304hL9jXQ69SRTMeGP9CHZEemVQfckmGR/AhNcYfxXqvfKu9xqRJ3tw= 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 Thu, Mar 13, 2025 at 3:57=E2=80=AFPM Michal Hocko wrot= e: > > On Thu 13-03-25 11:48:12, Zhongkun He wrote: > > With this patch 'commit <68cd9050d871> ("mm: add swappiness=3D arg to > > memory.reclaim")', we can submit an additional swappiness=3D argum= ent > > to memory.reclaim. It is very useful because we can dynamically adjust > > the reclamation ratio based on the anonymous folios and file folios of > > each cgroup. For example,when swappiness is set to 0, we only reclaim > > from file folios. > > > > However,we have also encountered a new issue: when swappiness is set to > > the MAX_SWAPPINESS, it may still only reclaim file folios. This is due > > to the knob of cache_trim_mode, which depends solely on the ratio of > > inactive folios, regardless of whether there are a large number of cold > > folios in anonymous folio list. > > > > So, we hope to add a new control logic where proactive memory reclaim o= nly > > reclaims from anonymous folios when swappiness is set to MAX_SWAPPINESS= . > > For example, something like this: > > > > echo "2M swappiness=3D200" > /sys/fs/cgroup/memory.reclaim > > > > will perform reclaim on the rootcg with a swappiness setting of 200 (ma= x > > swappiness) regardless of the file folios. Users have a more comprehens= ive > > view of the application's memory distribution because there are many > > metrics available. For example, if we find that a certain cgroup has a > > large number of inactive anon folios, we can reclaim only those and ski= p > > file folios, because with the zram/zswap, the IO tradeoff that > > cache_trim_mode is making doesn't hold - file refaults will cause IO, > > whereas anon decompression will not. > > > > With this patch, the swappiness argument of memory.reclaim has a more > > precise semantics: 0 means reclaiming only from file pages, while 200 > > means reclaiming just from anonymous pages. > > Well, with this patch we have 0 - always swap, 200 - never swap and > anything inbetween behaves more or less arbitrary, right? Not a new > problem with swappiness but would it make more sense to drop all the > heuristics for scanning LRUs and simply use the given swappiness when > doing the pro active reclaim? > Thanks for your suggestion! I totally agree with you. I'm preparing to send another patch to do this and a new thread to discuss, because I think the implementation doesn't conflict with this one. Do you think so ? > -- > Michal Hocko > SUSE Labs