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AJvYcCXiPEvRgy6uIp/GCgQ9WU0+Ia75BAxqGZh8H/gfVJUTybK12dQrEix/C9CTJVr+faaQcvJ4t2OFHw==@kvack.org X-Gm-Message-State: AOJu0YxGvZEThi7md6xEXTdAE2x01WXh8MHPKKp2XrLmBCvf7qR1mZ9K +tUaI3Z7XOE4HouGTqIA04uzcRWJNX+aZR6t0X2ZIyuUN8kweOKu4vLfNPFFU6youj/eTewbI7w meCjrL9643tpEyXQcetQOavMIo90= X-Google-Smtp-Source: AGHT+IHhFxiJIKOZQd9ObN+Bow9DnfeccCKDA+4HeO5e3KFOZo82DqxOsuBi8pqEMQvdlAwG2bxDBPuo1+y+Brz4sRY= X-Received: by 2002:a0c:fa49:0:b0:6cb:3bc0:c2c6 with SMTP id 6a1803df08f44-6cb3bc0c330mr53625576d6.10.1727455268393; Fri, 27 Sep 2024 09:41:08 -0700 (PDT) MIME-Version: 1.0 References: <20240926225531.700742-1-intelfx@intelfx.name> <5hnu3xa5hcusvmvg37m5ktsfcutghk2z3dh7lcoctyyfluabqv@u4ma5mafchpw> In-Reply-To: <5hnu3xa5hcusvmvg37m5ktsfcutghk2z3dh7lcoctyyfluabqv@u4ma5mafchpw> From: Nhat Pham Date: Fri, 27 Sep 2024 09:40:56 -0700 Message-ID: Subject: Re: [PATCH] zswap: improve memory.zswap.writeback inheritance To: =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: Ivan Shapovalov , linux-kernel@vger.kernel.org, Mike Yuan , Tejun Heo , Zefan Li , Johannes Weiner , Jonathan Corbet , Yosry Ahmed , Chengming Zhou , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Chris Li , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7B11D4000C X-Stat-Signature: q5jzexeejxwuqbtpikuxk9aarqnw5bxq X-Rspam-User: X-HE-Tag: 1727455269-347525 X-HE-Meta: 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 5ZUcPgE1 ZTtnnxMqVLR1PIX4T5OFIvt83a00qipozWDIXqLUQwWcn2QDL6plALSDNU1OUDMkK7SCZJuq3gKYwZgpy6pdY1B9EZaPcmiHw/5/oOcnKKQ9crCKTs9+tqkufcAqvhbG/yWfe9RyLS5xMUlbdt/pJacsupwLu0jqXjxJdWSj+JJ+DMDNizn22Ygo1wqkI9hk86rR1+jUC+UcmvWtWQEVWEk1vgkA00hb2eVse774w4/u+xDtCPNbX3zYvBFkLEn7RwTSsvFORLGDSpoFv4FRgkXgY+1aWnw916UFbIKfFJxTN84CvqAGxsLgpZ8DbWcGsG8dyspGJm7BtjgPI5LnZ0MGmB3wPftHRs6A9pCPlsnL4WOYAFPW4pNQQLLlS/JEpAr9m X-Bogosity: Ham, tests=bogofilter, spamicity=0.000844, 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 27, 2024 at 8:01=E2=80=AFAM Michal Koutn=C3=BD wrote: > > > What about assigning this semantic to an empty string ("")? > That would be the default behavior and also the value shown when reading > the file (to distinguish this for explicitly configured values). Yeah that's better than -1, I agree. Still a bit confusing, but at least the semantic is "we are not making a choice at the memcg". > > (The weirdness of 0, 1, -1, -1, -1 would remain. Maybe switching this > via the mount option could satisfy any user. Admittedly, I tend to > confuse this knob with swap.max.) Yeah a mount option, or in general some sort of global knob (with proper documentation) would be preferable. And yeah, I hear you with the swap.max confusion. That's why I tried to make it explicit in the documentation, because the difference is subtle and can trip up users. Hopefully, when zswap and swap are decoupled, users can conceptualize them as two separate tiers, and the confusion will lessen...