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[2003:d8:2f19:6500:e1c1:8216:4c25:efe4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a4ce458830sm6499970f8f.14.2025.05.26.01.14.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 May 2025 01:14:03 -0700 (PDT) Message-ID: <7d8a9a5c-e0ef-4e36-9e1d-1ef8e853aed4@redhat.com> Date: Mon, 26 May 2025 10:14:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 0/5] mm, bpf: BPF based THP adjustment To: Yafang Shao , akpm@linux-foundation.org, 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 Cc: bpf@vger.kernel.org, linux-mm@kvack.org References: <20250520060504.20251-1-laoar.shao@gmail.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: HFnx3PiWs8xf50YjzK_AjeKbQMla_S6O3MIEdGu0KlU_1748247244 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: CB69B140010 X-Stat-Signature: 1gmyzu9g5qnpwfd1aw9h5tzj67pdahpc X-Rspam-User: X-HE-Tag: 1748247247-407163 X-HE-Meta: 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 IfQ1gVnP 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 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: > Hi all, > > Let’s summarize the current state of the discussion and identify how > to move forward. > > - Global-Only Control is Not Viable > We all seem to agree that a global-only control for THP is unwise. In > practice, some workloads benefit from THP while others do not, so a > one-size-fits-all approach doesn’t work. > > - Should We Use "Always" or "Madvise"? > I suspect no one would choose 'always' in its current state. ;) IIRC, RHEL9 has the default set to "always" for a long time. I guess it really depends on how different the workloads are that you are running on the same machine. > Both Lorenzo and David propose relying on the madvise mode. However,> since madvise is an unprivileged userspace mechanism, any user can > freely adjust their THP policy. This makes fine-grained control > impossible without breaking userspace compatibility—an undesirable > tradeoff. If required, we could look into a "sealing" mechanism, that would essentially lock modification attempts performed by the process (i.e., MADV_HUGEPAGE). The could be added on top of the current proposals that are flying around, and could be done e.g., per-process. -- Cheers, David / dhildenb