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From: Shakeel Butt To: Jiayuan Chen Cc: linux-mm@kvack.org, Jiayuan Chen , Nhat Pham , Tejun Heo , Johannes Weiner , Michal =?utf-8?Q?Koutn=C3=BD?= , Jonathan Corbet , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , Yosry Ahmed , Chengming Zhou , Shuah Khan , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 1/2] mm: zswap: add per-memcg stat for incompressible pages Message-ID: References: <20260206072220.144008-1-jiayuan.chen@linux.dev> <20260206072220.144008-2-jiayuan.chen@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260206072220.144008-2-jiayuan.chen@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5B2FA18000A X-Stat-Signature: c5tqa6a99mkn5y8rn8ayfzz4nh11bah1 X-Rspam-User: X-HE-Tag: 1770400371-101793 X-HE-Meta: U2FsdGVkX1/PnS8m01w5yYIgjoNAxDz8Qkuo6We9aQNfiBeWG06wzYT/I4c04oDdbFMWX2lx2grEeeE6BsV5vaKq7x0GLeBLnCCAp2L/cgT7Nj2dg41DdK1IaOD+/rhu/rAt4J71hlF9K13G/zC19Ofei3yhMLdhXG1/+k1CvB5Ek8Lod8AY818hvMelW8GO7BFhBg7EgYq0Sk4cKhmOMZzxv2h6XGBkgziocnlIXtrM9wfOiJrN/4TT414zm4q0otDEH50CQmyxsCiCdU+gTv5slizSgpRWXVTD6va7b6by6bR6NuKWwXyxQwOOqJhJpVFSxHq6eAVDGgzCbyC5j6L3EfbFBweMN2YH2KqIhcK9MhE8Tf8ITr6jYCvm08VZ2DtpZMXp8d2qvS9WM+6LQBFGiDFfPHkFdWruEVS1cthvX2M70MbFu/FBMIKJOStFXwtEstwVZrHj++1dZTnM1PZJrTnpnHTDkFyzBckXxtlXuBm86C0v2SC6tEnmyrh3Ry2UfgA1jup0oJ0dyke14WXJxtECZzTHKdnaSyLiCe310zl4ArfBs5WrRCWxidcam1yEFNH1j9vvXxuW0Km2hKi5TF2VCw4dwl/B8t0IUADojJOteLHDAcu8jKIGOuTqA65DZl8Li0O2BHO2LF7R6W4msaiuEP6kisojJxr1/pOF4jbMNUPCHlve7ZWhbjyulPaVKHxZMe83oS1fNHc17DXlULBwoGAQr4x7Mr/IreujaL2qJyKFYWJCRsEoBtAJVg/X9MYpZXKgSd2ufeNyqpB+6reIFLXSYfuzsBNP5n8jlPKQB9GNurAojXNgTnBGvL+kB8JYT5LWC0feCAmeZfAVPFbWI5TE1UX6tpCvqQwqCn/JztxMQNHbZXcNqLk+zbaJdJVqldHR8ysfyA0R1+J1JdjLJriIC/TfceV3C6OV1D3OeMFGPiPomzo7Hx2iFKYBEV6y1LATKX/nkO+ ipacdwTn Ot/0I6Lq/APgmX1CIim1GE3M6ZYu2COOqzKemK4XH/jKG8t/BaHvV6fSVLqnt4kaW1ZlYq434uW1OrN6Y5WaGqcJFgekDqZdxK7uclrljEyaaT6L6SekA6VLqGTqL3NkaC4tI3HEIjfZHb1svwvIpqF3JVPUsS+NI7qbqr7R5KKEJ0SVyNYniuFhvrNhyDPBOeW/8+q332eeptMv3slzl5XuOysCg5Beu2l9lXzK54/oVuMZjfg1YHofj5MXZjnkHkp9O2j3fTfglBP5MXdcldblOk8ql72XWJWekNYztlhLHe/tZ0copYv4crSXw3OCIJV3x 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, Feb 06, 2026 at 03:22:15PM +0800, Jiayuan Chen wrote: > From: Jiayuan Chen > > The global zswap_stored_incompressible_pages counter was added in commit > dca4437a5861 ("mm/zswap: store to track how many pages are stored in raw (uncompressed) form in zswap. > However, in containerized environments, knowing which cgroup is > contributing incompressible pages is essential for effective resource > management [1]. > > Add a new memcg stat 'zswap_incomp' to track incompressible pages per > cgroup. This helps administrators and orchestrators to: > > 1. Identify workloads that produce incompressible data (e.g., encrypted > data, already-compressed media, random data) and may not benefit from > zswap. > > 2. Make informed decisions about workload placement - moving > incompressible workloads to nodes with larger swap backing devices > rather than relying on zswap. > > 3. Debug zswap efficiency issues at the cgroup level without needing to > correlate global stats with individual cgroups. > > While the compression ratio can be estimated from existing stats > (zswap / zswapped * PAGE_SIZE), this doesn't distinguish between > "uniformly poor compression" and "a few completely incompressible pages > mixed with highly compressible ones". The zswap_incomp stat provides > direct visibility into the latter case. > > [1]: https://lore.kernel.org/linux-mm/CAF8kJuONDFj4NAksaR4j_WyDbNwNGYLmTe-o76rqU17La=nkOw@mail.gmail.com/ > Acked-by: Nhat Pham > Signed-off-by: Jiayuan Chen Acked-by: Shakeel Butt