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Mon, 29 Sep 2025 23:00:40 -0700 (PDT) From: Yafang Shao To: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, hannes@cmpxchg.org, usamaarif642@gmail.com, gutierrez.asier@huawei-partners.com, willy@infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ameryhung@gmail.com, rientjes@google.com, corbet@lwn.net, 21cnbao@gmail.com, shakeel.butt@linux.dev, tj@kernel.org, lance.yang@linux.dev, rdunlap@infradead.org Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Yafang Shao Subject: [PATCH v9 mm-new 11/11] Documentation: add BPF-based THP policy management Date: Tue, 30 Sep 2025 13:58:26 +0800 Message-Id: <20250930055826.9810-12-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20250930055826.9810-1-laoar.shao@gmail.com> References: <20250930055826.9810-1-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add the documentation. Signed-off-by: Yafang Shao --- Documentation/admin-guide/mm/transhuge.rst | 39 ++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/adm= in-guide/mm/transhuge.rst index 1654211cc6cf..f6991c674329 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -738,3 +738,42 @@ support enabled just fine as always. No difference can= be noted in hugetlbfs other than there will be less overall fragmentation. All usual features belonging to hugetlbfs are preserved and unaffected. libhugetlbfs will also work fine as usual. + +BPF THP +=3D=3D=3D=3D=3D=3D=3D + +Overview +-------- + +When the system is configured with "always" or "madvise" THP mode, a BPF p= rogram +can be used to adjust THP allocation policies dynamically. This enables +fine-grained control over THP decisions based on various factors including +workload identity, allocation context, and system memory pressure. + +Program Interface +----------------- + +This feature implements a struct_ops BPF program with the following interf= ace:: + + int thp_get_order(struct vm_area_struct *vma, + enum tva_type type, + unsigned long orders); + +Parameters:: + + @vma: vm_area_struct associated with the THP allocation + @type: TVA type for current @vma + @orders: Bitmask of available THP orders for this allocation + +Return value:: + + The suggested THP order for allocation from the BPF program. Must be + a valid, available order. + +Implementation Notes +-------------------- + +This is currently an experimental feature. CONFIG_BPF_THP (EXPERIMENTAL) m= ust be +enabled to use it. Only one BPF program can be attached at a time, but the +program can be updated dynamically to adjust policies without requiring af= fected +tasks to be restarted. --=20 2.47.3