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Mon, 20 Oct 2025 19:52:53 -0700 (PDT) MIME-Version: 1.0 From: Yifan Ji <412752700jyf@gmail.com> Date: Tue, 21 Oct 2025 10:52:41 +0800 X-Gm-Features: AS18NWAm93w4E1HR9wlOqKTla8-E3h1y0PBY8xr1ipyO95k053_X_h4pbXOyqw4 Message-ID: Subject: [DISCUSS] Proposal: move slab shrinking into a dedicated kernel thread to improve reclaim efficiency To: linux-mm@kvack.org Cc: Andrew Morton , Michal Hocko , Johannes Weiner , Vlastimil Babka , Matthew Wilcox Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AE55540003 X-Stat-Signature: pak3rcosscqpt1pbgiecheh84bbtew96 X-HE-Tag: 1761015175-115697 X-HE-Meta: U2FsdGVkX1/Uy/hi8Xhl7s+NlOFK5cXB+vjbsvHjVjKLKEPB6Mo62TWjtC/cXYnxScpLcSaQGuhZ5cSknfZYpBA2BR1+qXSYE/WJ4EXmIctpGOxNXSbFleoEmhqVyRlXDzsg7/xEJaH4vFwA6frhocmGz4fKsyHpXMN3PbrUWvCGQjRBglDhxOS0oW7LuAbuL3PS78bknsIMEWFdQF8kGV3fS0RFhzXjqnTxQS11LTt7/mbpDhf2dYumRrB+PH/UPZLk2CBp5faTSNWRsfRDvfD5R/uBA6+9mTplzS0NspKl9kXepEbmX2/GIStzjrdLHzqbGoqdQl4ihRAHc7sqassyts5ouUNcqMcOWP86f74ZbRXN8Z0BS2dl8SJPU57+i833+YFdFYWH2eroHt6qI+IdUwaivKZDxnWaV0it9LORFql7aWh8QArXhHQSYXUIYUsCQ60Knoc+bfHbDt2i7vrW7bxvhELMTDz0rcoycrUmxMJD1JartE2z0IHfUyJfMuM8j1Q1DDYKHyX389DyftCs452Ve5mv0L6ftn8CoH4otm/ghHJtnEus8Whg74W3S15DLvs9WINRTSx1OJ3e+li4JEToT26g5/r/7f9u4ILay7csYDMOtJCLALYIrEIaY3FOK+Tj1JAXg59//J+6LG6g51CdzUJITom6dCRVggGSEPyrydIoZssOEL6R1SxJMbXRzuNk8K1bXzNr2gvJoHLJcFdPjU9JUU/M/ftHp1Z1o/mp6INuyLHC0VLQtbgxS954F8q1uMWdwbKMSVWaV1xmNZHPm9k3O9mKdCaYtJXOZw6M16uTY/7kBStWWaNAGFPwRn8wtmfrfXJmhuQhUTsDjz7DjVj3wQ/cCWG/1uYtg1H7s+I9TmLNNzu/qWfWQ+A0djellrUpIkB263A6uCGQFtYFogsV/o/865khi1erAMJ3wfiT0e5AIJpgBxXlw5KQlOi6WU7Iqid8rts FQEeAKpH z9mJIrnDNxPOfe2LN6hCN3eRjIZfQPRCwhKat9Jfukp0kyIeqpuNEt0/wAN73HdxjzgV0FieC7a53vu2Bl/N3cBW4ZAjrrdEESYghQgsJLMm1FWI9cXv6+gCyqAqWTHbjZNfazVMLh9lXNsn/URTDijLCEsIDluqXe5ulArDCjE59VL6m55JlF3Kb+IXw5xUcVSKJdB453rCVvXPeWZ30/heLSNInb5cMR24kzGvzE6mi00hLnE4AZqCRqi89AOt7afLJn+rCRFVnvTomCTcaEg78Fwi3JTMKAC1NKBFLuHEPRS/x6eNqNcClZRkmFIjTXe2rS+tkrh4myl0NgFHzB4ZauspU6wqLFFU9 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: Hi all, We've been profiling memory reclaim performance on mobile systems and found that slab shrinking can dominate reclaim time, particularly when multiple shrinkers are active. In some cases, shrink_slab() introduces noticeable latency in both direct reclaim and kswapd contexts. We are exploring an approach to move slab shrinking into a dedicated kernel thread, decoupling it from direct reclaim and kswapd. The goal is to perform slab reclaim asynchronously under controlled conditions such as idle periods or vmpressure triggers. Motivation: - Reduce latency in direct reclaim paths. - Improve reclaim efficiency by separating page and slab reclaim. - Provide more flexible scheduling for slab shrinking. Proposed direction: - Introduce a kernel thread that periodically or conditionally calls shrink_slab(). We'd appreciate feedback on: - Whether this decoupling aligns with the design of the current reclaim model. - Possible implications on fairness, concurrency, and memcg behavior. Thanks for your time and input. Best regards, Yifan Ji