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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v3] mm/vmpressure: scale window size based on machine memory In-Reply-To: References: <20260305043038.2176-1-mcq@disroot.org> Message-ID: <31c4680848b833d53b1979b45d5a368d@disroot.org> X-Sender: mcq@disroot.org Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: CD8F4180006 X-Rspamd-Server: rspam07 X-Stat-Signature: eymxzbzns4nztan9gaz69wpjrmtwmoox X-Rspam-User: X-HE-Tag: 1772815451-982510 X-HE-Meta: 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 s1Pfmn3+ gInKg3AYTi5nRRp+jhOmnJUQ5oonpYMwPpF8KQWiWZ+HAp5vkN7aUx8CIPXydx6JpUFxNpRhSOd2GbL4BmTRtktmiqo3Mbc6WDlmLVpWRIsW0QsPtFGRkMk1LWDv5DXqFp3GHlEgaR8SNpFDO1tcCUtFTj9VebX0wWPiOst3zhp/t3bEH2Loe7bQt1Zq0pEt5BouktQbeSfMcMEwPpVuA95hlaTjJohSwO//A9abEdqcuLsk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-03-06 16:52, Michal Hocko wrote: > On Wed 04-03-26 22:30:38, Benjamin Lee McQueen wrote: >> the vmpressure window size has been fixed at 512 pages >> (SWAP_CLUSTER_MAX * 16), ever since the file's inception. a TODO in >> the file notes that the vmpressure window size should be scaled >> similarly to vmstat's scaling, via machine size. >> >> the problem with fixed window size on large memory systems: > > Thank you for this much more detail insight into your thinking. This is > a good start. I am still missing an overall motivation though. Are you > trying to address a theoretical concern (the said TODO) or do you have > any practical workload that generates bogus vmpressure events. yes, as i don't personally have a workload that explicitly requires vmpresssure to not generate bogus events, it is still technically a "bug" that can still be improved. i believe many legacy systems would benefit from this as they still use vmpressure notifications. i agree PSI is the preferred interface, but vmpressure is still used in other production environments, like Android's LMKD, right? -ben