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Tsirkin" Cc: linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Johannes Weiner , Zi Yan , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Alistair Popple Subject: Re: [PATCH RFC v2 02/18] mm: add pghint_t type and vma_alloc_folio_hints API In-Reply-To: <290d615a001cf121dc0c604eb79451bcc7917baa.1776689093.git.mst@redhat.com> (Michael S. Tsirkin's message of "Mon, 20 Apr 2026 08:50:23 -0400") References: <290d615a001cf121dc0c604eb79451bcc7917baa.1776689093.git.mst@redhat.com> Date: Tue, 21 Apr 2026 08:58:59 +0800 Message-ID: <87pl3ti0x8.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: 1ieu5girn75raxwc11onyobyn1shm1yi X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D978B40010 X-HE-Tag: 1776733144-269157 X-HE-Meta: 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 wgKQ4ORm TjyvRNOPTTArNQ68tSqQLFR4ISWZbeSox91+o5FPAio4JHe6R8nS2KU4FAVJmqlOqqbtYsERYfoWc2ZcbPPAgVDbYcQ7CFNt3y9LC6GZyGgKVBKFlaxS8XU1dBBvl3lTm3uRgNyf0VCjnxHOwSQfDE2gC5Qey/4xgwG5pP5N2KOGEy2vUwD9LR1M2mIY9Sh/K6PBLl5IRrPlA9qZ3gzxpSv3d8NHGpxIKa5UVxaLpfJykflhzpWLZCOyVX1N5K2f5V3PSfow91w1ILI2JVgaC1TmqmUqSoQq96r2vLS3uBvyFBz1mtZlR1DPZeD5hGYpHOFPtq5gIhtbS/5pxYrvs0uaJEIpHRrPnp7cwjlLsqgvZM1Rb8lC7lDqTImRPYvtO/1qBAsGSUzxXKJ53Hz88QEpQOrZaMLXp2OFe Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: "Michael S. Tsirkin" writes: > Add pghint_t, a bitwise type for communicating page allocation hints > between the allocator and callers. Define PGHINT_ZEROED to indicate > that the allocated page contents are known to be zero. > > Add _hints variants of the allocation functions that accept a > pghint_t *hints output parameter: > > vma_alloc_folio_hints() -> folio_alloc_mpol_hints (internal) > -> __alloc_frozen_pages_hints() > > The existing APIs are unchanged and continue to work without hints. > For now, hints is always initialized to 0. A subsequent patch will > set PGHINT_ZEROED when the page was pre-zeroed by the host. Why do we need this feature? Is there any performance impact? If so, please provide some performance data. [snip] --- Best Regards, Huang, Ying