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Mon, 27 Oct 2025 15:46:21 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Nhat Pham Date: Mon, 27 Oct 2025 15:46:10 -0700 X-Gm-Features: AWmQ_bma6lyHlpvPtwTt1egk70m2KnBJDjgat6AjIDzKFfoBCYrn6d-bXve4s8M Message-ID: Subject: Re: [RFC PATCH 0/3] Introduce per-cgroup compression priority To: jinji zhong Cc: minchan@kernel.org, senozhatsky@chromium.org, philipp.reisner@linbit.com, lars.ellenberg@linbit.com, christoph.boehmwalder@linbit.com, corbet@lwn.net, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, axboe@kernel.dk, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, akpm@linux-foundation.org, terrelln@fb.com, dsterba@suse.com, muchun.song@linux.dev, linux-kernel@vger.kernel.org, drbd-dev@lists.linbit.com, linux-doc@vger.kernel.org, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, zhongjinji@honor.com, liulu.liu@honor.com, feng.han@honor.com, YoungJun Park Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: C9586A0006 X-Rspamd-Server: rspam03 X-Stat-Signature: kw4n1t5u4fuyaozogj6ry61q7mhkn1co X-HE-Tag: 1761605183-319862 X-HE-Meta: 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 UILY0S25 3XxjpZYTXgNkrEG3jh0h3q5V95n8SAYCfJM9GJvH45DHmvgr++VH85k8uKZyGI1kmWRHHkrQNWONWkR+qtK4WY1ht+wQ/zADyJGme+v8MsJtq6g/TXHVQvbC9nfQ0LybrcQT4chuphFP3bPgYt2mdA21OpCC1uEfDYdoKbKAq8T69X5BYU1H35rCIp6zaTjIaQP6qMvfqp8R9Aq/wS75d5odFxRfT4wPzhzKOiKL15lzCIHhLmrJQuhGiCh+5JWNpr1zhRuI8io6ICd5uHMoCtQ7r/up16OV/cXraX0blUHSxIcqnKpGGa+cZv0ceyVPWCJHlRpyJzZEob5rJPwph8u0zRT6PhXz4ptB0WRz6dQLlPuZqxL0IisegX726yywl9HxvaPbdDc3UCPcspO7KrtgHR++3FbnQ51xteGAfSQdoLaR7asjWsT49BGzYk9ID+VrJg1l6cmD2qONzGO8uAde2zk73dEhhjxikY6pKe3NnQrfQk0Bo+VQsfQ== 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 Sat, Oct 25, 2025 at 6:53=E2=80=AFPM jinji zhong wrote: > > Hello everyone, > > On Android, different applications have varying tolerance for > decompression latency. Applications with higher tolerance for > decompression latency are better suited for algorithms like ZSTD, > which provides high compression ratio but slower decompression > speed. Conversely, applications with lower tolerance for > decompression latency can use algorithms like LZ4 or LZO that > offer faster decompression but lower compression ratios. For example, > lightweight applications (with few anonymous pages) or applications > without foreground UI typically have higher tolerance for decompression > latency. > > Similarly, in memory allocation slow paths or under high CPU > pressure, using algorithms with faster compression speeds might > be more appropriate. > > This patch introduces a per-cgroup compression priority mechanism, > where different compression priorities map to different algorithms. > This allows administrators to select appropriate compression > algorithms on a per-cgroup basis. > > Currently, this patch is experimental and we would greatly > appreciate community feedback. I'm uncertain whether obtaining > compression priority via get_cgroup_comp_priority in zram is the > best approach. While this implementation is convenient, it seems > somewhat unusual. Perhaps the next step should be to pass > compression priority through page->private. I agree with TJ's and Shakeel's take on this. You (or some other zram/zswap users) will have to present a more compelling case for the necessity of a hierarchical structure for this property :) The semantics itself is unclear to me - what's the default? How should inheritance be defined? What happens when cgroups are killed etc? As a side note, seems like there is a proposal for swap device priority (+ Youngjun) https://lore.kernel.org/all/20250716202006.3640584-1-youngjun.park@lge.com/ Is this something you can leverage? Another alternative is to make this zram-internal, i.e add knobs to zram sysfs, or extend the recomp parameter. I'll defer to zram maintainers and users to comment on this :)