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AJvYcCU44emqTW70xbanFHpZM62MSOxfIS4FHkrfAG21MsbVM3IJj6a9I0I26PLHo+HtAvrT5HlSWeVAdw==@kvack.org X-Gm-Message-State: AOJu0Ywvit+XnBOXjSdgv3PxThfloMMNdvZUTB8h5LtCQt115tO2xB0v buJTbMrXleVI5ndJkI0pG14nKc3+4NNsJSE6i8IPIWAhlDq1rj3Ju3NkKvzkAFX6S95UjOqLSyY fg5NKh06XbfJryO+huW2jCeSmGsagQZs= X-Gm-Gg: ASbGncvpssGT/NHZN/rAE0vy5V1+s5DLmD3+bcZkKkc0QlEbN6X7Uat0rOoK4UTVxlw +qk6ilqQUnC3wNwMy9gwJlrTeyYlNzKOMi14Cy/yrhDBzD0kJ6ZMqZ4tTjKZHDuZBlAg8/TL2sg 0Uz8uCa/SWEj380qQWtawnVB4xPJeJjpK1SDxfsdudjlJ5QhF7WLEteakGdXRWztbh4ceVt46XU DwQJIkVMCAeNBwZpj0vT5kgqo+FlHUWTugjbspo X-Google-Smtp-Source: AGHT+IEjqFiMZ84yVMmL8aqHzutnqyfPVAvHhHZi1w2Zyv0MzO2zv3PyHq0KNksiUWqn8ZVtvz5/v5ORndsZtS+GvZ0= X-Received: by 2002:ad4:5742:0:b0:7e4:ee39:738 with SMTP id 6a1803df08f44-7fc45d03d94mr42335986d6.67.1758800317940; Thu, 25 Sep 2025 04:38:37 -0700 (PDT) MIME-Version: 1.0 References: <20250910024447.64788-1-laoar.shao@gmail.com> <20250910024447.64788-3-laoar.shao@gmail.com> In-Reply-To: From: Yafang Shao Date: Thu, 25 Sep 2025 19:38:01 +0800 X-Gm-Features: AS18NWAPI6UtnnMnTVeKsaXnI6UeT7SK4r6__DsbeZCo6L2UhwRp_pLiTM-6Da0 Message-ID: Subject: Re: [PATCH v7 mm-new 02/10] mm: thp: add support for BPF based THP order selection To: Lance Yang Cc: 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, bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 3aeygnp4qoyu73cde8x669oxxgjdj1g3 X-Rspamd-Queue-Id: 3017D100002 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1758800318-476011 X-HE-Meta: U2FsdGVkX1+6ObDkYTj0H174aSN7+2cDVDAyHsZrY8zJIDJyZG7SfawejHGK/3E+il3T3YZ5uUvl38scmVC2wER4dCcwaS5M8dtw/AcuMJk0uLCeLZq2fnNbfrlp/mXgbDK+tbpnhn7SnUmdIREKbFpwmCpYiOV/eipSKGn7CCAzEQUaDE0JbsXg8uBQdRcyhbOaNuRKgOf1x5MBRyodUW2HXfl6SoNdPUt04FUBWNNBFDsupSKcfr33g3TgANZTCCLEL0+aO8qqQeaR+Q7u7zaKIlFCxHrHFr892xsXxJiWYw12i/n25wpXnDpJdOET+6e6vl98tPJ3FEjcDFQAyOKlte+QnRdjQghSDQNnTSKx9jp6D8rH3eQiwwfifHzUFECuJ73qhHk5ks6iDpMCANtb59jWGNCzH5im2/fj4UDqth/MKzcUj4G3ad1Y3XBXZ7nP25oq0G38V6pc4O9Tc3VQsoa4nzn4tu7K0b9JCq0ep7ekrfflJkJhHBentQWdByfE5v8p1EQ1o8IDqW0JvWDalkeXME6VmeZI6Ps2jXbFnZuvH49Vc4YVEWrrsw6HJUd3/cZ11ZBaqU7SpiiDpGbfwsbGrVusvqLZZLwqEEFa53KiSQ6x2FNoLHJQj619JKJ3R4obM//J7e5aoNh7X5F2w7dJHtGpMUjU2vGyxjKE+h/MOwpUrAKZB7t0U4TByC2mV/wIj092+9wVteIz1kAi2y/ukDzW7Pq6KDzVdTI0qb2SZhUhOfjZtYMwmsregx/wAdKplzfw8+CXctvL/sU2pC7NAogF0tdB0vbpLxrhlovuJerBrI7x6KGZhC3TuBNONlbCtvai3VbvobqQgPeH+NMJnTIeuHn5u8PrRtTodafXlxwmYaFfAJxZmige07gz5LXolop9XvLQgMVQ8HpfORBMirgYC6DqayA6WJxF5WxMpaR/+FL4XLNLilUbUXgdDKemBmaMWyy0vDv ACGqnR+5 PZ/Od0dY9CiQjohA4gIGrj8mnzLX38w0uUyeYI5hKyji25C/SFXUTLs/8NUITQxAR2/xzaQMKJ82pl9XBEsk/DoAFcixML8PXQy+kTeuAgF1odtMU1K7kMNyAny3yFA7TpsZ98mTeZAUXetH6bbGmLwORr3KEa2itcBWaObDI/aISso+/OsKYde7TOaVtvidXN96ZgMGHSIgBGImWNrfj30Erz2dsii1zqCp7qYnib3jDKKhc1eGJ6A1bL1x+MDfWxC69aDhVl+jCSPvd2wAdioiYlVPXcM+iQ3FLH6teZFsEs7jT8Pc4HmSN7AK7mFxMxDrRDbDjA3rdzPbXGuyPMVt2tFhOw15QnWNQGqQ82LJr75AcwkBKF5+YdTk0JXOZL+nOXja1CfN0zXbW3Kb+5cYOqgDpnc4R7qECs28RA1IOdCWsqw2qWt2cXBBlheAoy2TP0NLeqfRDoBk= 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: On Thu, Sep 25, 2025 at 6:06=E2=80=AFPM Lance Yang w= rote: > > On Wed, Sep 10, 2025 at 10:53=E2=80=AFAM Yafang Shao wrote: > > > > This patch introduces a new BPF struct_ops called bpf_thp_ops for dynam= ic > > THP tuning. It includes a hook bpf_hook_thp_get_order(), allowing BPF > > programs to influence THP order selection based on factors such as: > > - Workload identity > > For example, workloads running in specific containers or cgroups. > > - Allocation context > > Whether the allocation occurs during a page fault, khugepaged, swap o= r > > other paths. > > - VMA's memory advice settings > > MADV_HUGEPAGE or MADV_NOHUGEPAGE > > - Memory pressure > > PSI system data or associated cgroup PSI metrics > > > > The kernel API of this new BPF hook is as follows, > > > > /** > > * @thp_order_fn_t: Get the suggested THP orders from a BPF program for= allocation > > * @vma: vm_area_struct associated with the THP allocation > > * @vma_type: The VMA type, such as BPF_THP_VM_HUGEPAGE if VM_HUGEPAGE = is set > > * BPF_THP_VM_NOHUGEPAGE if VM_NOHUGEPAGE is set, or BPF_THP= _VM_NONE if > > * neither is set. > > * @tva_type: TVA type for current @vma > > * @orders: Bitmask of requested THP orders for this allocation > > * - PMD-mapped allocation if PMD_ORDER is set > > * - mTHP allocation otherwise > > * > > * Return: The suggested THP order from the BPF program for allocation.= It will > > * not exceed the highest requested order in @orders. Return -1= to > > * indicate that the original requested @orders should remain u= nchanged. > > */ > > typedef int thp_order_fn_t(struct vm_area_struct *vma, > > enum bpf_thp_vma_type vma_type, > > enum tva_type tva_type, > > unsigned long orders); > > > > Only a single BPF program can be attached at any given time, though it = can > > be dynamically updated to adjust the policy. The implementation support= s > > anonymous THP, shmem THP, and mTHP, with future extensions planned for > > file-backed THP. > > > > This functionality is only active when system-wide THP is configured to > > madvise or always mode. It remains disabled in never mode. Additionally= , > > if THP is explicitly disabled for a specific task via prctl(), this BPF > > functionality will also be unavailable for that task. > > > > This feature requires CONFIG_BPF_GET_THP_ORDER (marked EXPERIMENTAL) to= be > > enabled. Note that this capability is currently unstable and may underg= o > > significant changes=E2=80=94including potential removal=E2=80=94in futu= re kernel versions. > > > > Suggested-by: David Hildenbrand > > Suggested-by: Lorenzo Stoakes > > Signed-off-by: Yafang Shao > > I've tested this patch on my machine, and it works as expected. Using BPF > hooks to control THP is a great step forward! > > Tested-by: Lance Yang Thanks for your test. I will post a new version ASAP. > > This work also inspires some ideas for another useful hook for THP that I > might propose in the future, once this series is settled and merged ;) Excited to see it! --=20 Regards Yafang