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b=o3vXRIxEpK23GyO+mY6d52E5k2taD8BCE+4O3YDNni+k+sBFyuoUMgr8ra5ibrrtJ hGljfUIJbr952NnmS3sxPS6JxBIJrgD3Qfs+QXEhMnJR6OKeHoPsIdffeXQllAPcQh Z0LkIvHBr4ML8gRRlK3wmdqD80khBT06Vw3NXSMKYDw2Z/isd5nMv2oY0VDuV0llm8 UfcP6QfT9aED9bwIIyOyDGENI4vkFicmQsvcQh5hkm/DXnLC0L3GFJ2Mq7lfCKd8YX ftnTl9ivxsChN3MWvH9gV6soMaHw+pftMf05/wytW82F6de4FmSQmS/bsmA+y4bU4E +zQlDgdWwyZBQ== From: SeongJae Park To: Jiayuan Chen Cc: SeongJae Park , linux-mm@kvack.org, Jiayuan Chen , Nhat Pham , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Jonathan Corbet , Michal Hocko , Roman Gushchin , Shakeel Butt , 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 Date: Fri, 6 Feb 2026 17:21:18 -0800 Message-ID: <20260207012119.69369-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260206072220.144008-2-jiayuan.chen@linux.dev> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: F3B1E18000D X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: je3mzrociffpxoki15rsditz5qu83dfs X-HE-Tag: 1770427284-39635 X-HE-Meta: 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 1hgI4j2R MSzsAW4OpZxnHKmwtNMesJQeZw3HaJZWt4vGcx2nlX3GsCYFEb/xZB9vC//pLUcz6TqWiGbhhso/DQ9vG+9egC8y4K3kSuY2yblXCTm8NXsNlw08h2gWEgPlUTmT5ZoUTorBUnkPQYJLDlHdtlMHTDafytX1hbAaYzmkolxHTzy37zcN3wuQuosXQJ+Gy/Jkblx2pxhpyFZ+gnqjG8SRT7nlNppXNdC1EXKHQ8ToFkT5/PzDmpj65zunhq1y0dVVKeE1cCKuAb5aYQIZW2Qws1MlFMYy39YyduQM1zbgW3/eFYSQ1hPE4Yzguag== 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, 6 Feb 2026 15:22:15 +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. Sounds like a useful new stat, thank you for making this! > > [1]: https://lore.kernel.org/linux-mm/CAF8kJuONDFj4NAksaR4j_WyDbNwNGYLmTe-o76rqU17La=nkOw@mail.gmail.com/ > Acked-by: Nhat Pham Nit. It would look better to have one line before tags lines, or use 'Link:' tag with '# [1]' like trailing comment for the link. > Signed-off-by: Jiayuan Chen Reviewed-by: SeongJae Park Thanks, SJ [...]