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AJvYcCVnAlXEtBbOWAqUVXBOgpNtcFZ7y07OWmisbTTelfuYyVQCKkwlN3Uk5fyOBOaRKIf9oTUktKQ39g==@kvack.org X-Gm-Message-State: AOJu0YymNxRGen6p9QGsR9E6D7ACzTAaUU5SLtA0C/Z3nHJPKe/Cy6Br +EbH/65MolLSZYoK/S4tsZGmJ/CmEBRj0xIs12cQ8g2qTz35dfo8ym0cHYZOcOOnrezBNNzBADb FTri4nrl73NKFWdaXP0n0NY7FjzMN9I8= X-Gm-Gg: ASbGncv6T/6OXSUto8abJV8+KmpMV2J1yYN4064yGTuTvLALspKflIt5Tdi3tnsaZdK PlaFe4LybwNI/GbNGcFcdA0L9WnL9v2kh7WAF1pA7smFiYdB77jHIAaJzQE2XM1NM/K3d6ut+IB 7cf0FuGHgGKwmKMXyIFnHV0sbGRXOIRkl/41Wuclh6dpcsf3HqlkAa/eIMWPHCWjXi9cY7NnsuG JP/VZEHDYegLbK1hIU= X-Google-Smtp-Source: AGHT+IF8WVpB/g1JMlOdobaIjwrWwlXDO20YTmdhB82E33R4jbv8LdlESlw9MlPJrT6Dgk8ja2BuPEbvb3+xGqZlJy8= X-Received: by 2002:a05:6e02:164e:b0:3fc:d8b1:7a96 with SMTP id e9e14a558f8ab-3fd8e98d13cmr6645145ab.8.1757108124237; Fri, 05 Sep 2025 14:35:24 -0700 (PDT) MIME-Version: 1.0 References: <20250829162212.208258-1-hannes@cmpxchg.org> <4vpqew3bfs74kesmgd6kaafgm6nr6zbtt2t3hl2khkc6ds4zep@hllgy77hdumf> In-Reply-To: <4vpqew3bfs74kesmgd6kaafgm6nr6zbtt2t3hl2khkc6ds4zep@hllgy77hdumf> From: Nhat Pham Date: Fri, 5 Sep 2025 14:35:12 -0700 X-Gm-Features: Ac12FXz1xIEuR5P_UzNwabExfIPEV8sQerJraRtHn2GEfVW4UeX0axaUNE1zkPY Message-ID: Subject: Re: [PATCH 0/3] mm: remove zpool To: Yosry Ahmed Cc: Johannes Weiner , Andrew Morton , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5C6734000A X-Stat-Signature: 6grc73fnxzsbn8mama4s8dcshw8eyn64 X-Rspam-User: X-HE-Tag: 1757108125-150432 X-HE-Meta: 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 7jz11lHJ E9faLWjFi1FcuVrdgMN8msyyEdkCoP3cWmK+ecoRHtULjGIuf1uiB4h4/bLGnYnvL/Nocfl7BpQKk8Melt+yRr/b2m3iS47sN4U4KIp5ULuhtKV8Py5m+/ew5zxfr4p7v9pHpTE+1KIU2CsIwibOT7kMNZX3Cpie05eyOrHPUhgY82gTPWVHa0DvYag3AB6/GhKqKrJ47Wg9PKsdcQVMBCbc52G3oHrOkyyc/sY+i8VcFEPn1tLetXLGsVHJJI3rRj72zdi+mpm27quKReXXC2VqGlwNycAa3+izPANSojnRQXUabFzNcdk9POTtt2mjIqwj/MnO7gYGRgdcNPRrYffxFDMlOiwpg6NePDSG8NAlSKRl33rqVPja/8gnyJ6lFSTiD105VeZPsTI46TVJmN2elNxCj2wUlVMDJ 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 Fri, Sep 5, 2025 at 12:45=E2=80=AFPM Yosry Ahmed = wrote: > > On Fri, Sep 05, 2025 at 10:52:18AM -0700, Nhat Pham wrote: > > On Fri, Aug 29, 2025 at 9:22=E2=80=AFAM Johannes Weiner wrote: > > > > > > zpool is an indirection layer for zswap to switch between multiple > > > allocator backends at runtime. Since 6.15, zsmalloc is the only > > > allocator left in-tree, so there is no point in keeping zpool around. > > > > > > > Taking a step back, even if we do have needs for multiple allocators > > for different setups, having it runtime-selectable makes no sense. > > Honestly I think we should take it a step further and make the > compressor selection only at build/boot time and completely get rid of > supporting having multiple pools. We'd create one pool at initilization > and that would be it. > > I believe this will simplify things considerably, and I doubt changing > the compressor at runtime has a valid use case beyond experimentation. You are completely right. And, even if there's a setup where we benefit from multiple compressors, the current setup is definitely not it. How are we realistically going to use these sysfs knobs? Change to one compressor, then quickly change it back? How is this remotely useful? Let's remove it all. In the future, if we want to do multiple compression tiers, or per-cgroup compression algorithm, we will need a completely different architecture anyway.