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See http://www.infradead.org/rpr.html X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 0A92280002 X-Stat-Signature: u38o6uh7gqfn7pg49mf8mpjujrb9khaw X-HE-Tag: 1787729744-264437 X-HE-Meta: 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 hN+CK1pV 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 25, 2026 at 09:39:14PM -0700, Christoph Hellwig wrote: > The other callers of iov_iter_extract_bvecs matter more, but this is > the main user. > > And iov_iter_extract_bvecs right now is very inefficient when used > on larger folios, as each call to iov_iter_extract_bvecs and thus > iov_iter_extract_pages and iov_iter_extract_user_pages can only > fill in up to 256 pages. On x86 that is a single PMD mapped > folio. Passing down the bio_vec array means that for PMD-mapped > ranges we reduce the calls into pin_user_pages_fast by a factor > of 256. Also in addition to reducing the calls to pin_user_pages_fast, it also removes a fair amount of work to recalculate the bio_len in the get_contig_folio_len loop in iov_iter_extract_bvecs, which has shown up in profiles (although only marginally so).