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Fri, 16 May 2025 11:20:45 +0800 Message-ID: <9c54397f-3cbf-4fa2-bf69-ba89613d355f@linux.alibaba.com> Date: Fri, 16 May 2025 11:20:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 06/12] khugepaged: introduce khugepaged_scan_bitmap for mTHP support To: Nico Pache , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: david@redhat.com, ziy@nvidia.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kirill.shutemov@linux.intel.com, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org References: <20250515032226.128900-1-npache@redhat.com> <20250515032226.128900-7-npache@redhat.com> From: Baolin Wang In-Reply-To: <20250515032226.128900-7-npache@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Stat-Signature: 49j5xypxh4ozqx7uxct4pqo8cfmp1nth X-Rspamd-Queue-Id: 14DA120003 X-Rspam-User: X-HE-Tag: 1747365651-125687 X-HE-Meta: U2FsdGVkX1/oubmHODm7+tP8nekmTYiWpuQIYA/U5zDJv6GgeQgVXTgXsYkkbsphst9Cx1juQ6K+kEZskswRTlveg02XGfE/QIk38F2IJsLNCEwtUzx/3gqnSc8LuVBgJ5iG8oVEPvxwAQ/z9SlA0XhyqsntcS1dw7wLlAeOaty2NZdIoKQNnMdXuP6V2UNxUSaVsACxj7v0Iii7wtmvtsMtVhG+2/b6ELdvh37VZtE3TeR+RLXLpvdp04jdT27X8imbe62TXgTHzL+NhAi3ZYu9bN120VqZQWOM6fhzpSPjfHFQK2Nud+8cdcYp/womN9b6vwOxO2gJb9fwvEpmZNXOw+KOiep/hLYA4XuOYgzIqaG8poVZySGpJo5uzesUoTxcJPYgwDRXFx7yoUF4GIGJ0i8EhnzYvhxN/owPK5dvjTxciUgRTdZPq6Q99ZCSnracntpH/cHe5zxi+41hmb8CzTopBy2kpBZIarHindnEsuu2tc4YaD5ppHc+URf+1ghenx6jRcryjDzZfJbL4/OrgFT+kgGxBh/sMaQiGiGzRSOcx2YY/u3uJN0HMtpfThT2LEs+AWfiU1Jon4HAFyFWcOaZ/q8EYvcUAi3aq7A6Piu5Kehz537hzS6grV5R0ahKYut2FoMDvlrFAlGCIDroS9dcyYdGdkQIuTae4cZKsSVredj1GnSR2wMxGzNoCyHWAnbKLZYGaZGe6RixYsABP56Tl86B3SYCsu3rbMuXyM2bvAD9I0lL6L511L8j1Shp1iFfRgCgIvd4xJaLbIEbleFLQNAHvrCVZ8JBZRj9btZvX4zEaE5ExIThuUvtkQrWgU1ZRrh0EPp3NqFRvB9n7NRon6weDbAzlnOaWmrc43ncbvJcTYo7eRKYKztAftXRMtfxrFIAmY949e+H43QfRXOwk5E4hS95iOa1jlluWenb7RKO17V+p6K+vSYrzL7NXo1HpRHDTjhPkiT 1NszwfJv sqfS7DvdJnpCLmC2KnhnnTCy6/pprFY5itzOgmREH+L2vZmNyl5Q4DyV2MLOYAqL/EVbD3a+RWE/JMCBdThU7U308Owrc02WPuLFYTbgNNPlaEUpwu59sM6ytAWADd3rzgpVs4lQ+h79ij7gvt+IlR45uss/9VBRa8eiKyAtIxxdf5BkLvztfoFOB7EhBvY0wZ2TzHQe4KTJU9xXl/TxqXLgyt4ginHBeO7xdDbC0H3GCFCuEpxHJMKDoNHQLax8j/4FPM79+a5gDcmMcJ8nVSq9f/Fn2Rshg2TK/Kma7kLZoOzHumPp9EqYIMULLyu+SaKyVJ604wK6iuf2kgd6KAZD5R/hPsaIWfCuo4ciWJIyeZevOPyxiWhu1Sm5O12EX1gyDk5EWxKehfINRPLG8a4ZT524JsGWUfKI0wNyE8tLpMdSju4MjLjI/fe0cn7lakwwz 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 2025/5/15 11:22, Nico Pache wrote: > khugepaged scans anons PMD ranges for potential collapse to a hugepage. > To add mTHP support we use this scan to instead record chunks of utilized > sections of the PMD. > > khugepaged_scan_bitmap uses a stack struct to recursively scan a bitmap > that represents chunks of utilized regions. We can then determine what > mTHP size fits best and in the following patch, we set this bitmap while > scanning the anon PMD. A minimum collapse order of 2 is used as this is > the lowest order supported by anon memory. > > max_ptes_none is used as a scale to determine how "full" an order must > be before being considered for collapse. > > When attempting to collapse an order that has its order set to "always" > lets always collapse to that order in a greedy manner without > considering the number of bits set. > > Signed-off-by: Nico Pache Sigh. You still haven't addressed or explained the issues I previously raised [1], so I don't know how to review this patch again... [1] https://lore.kernel.org/all/83a66442-b7c7-42e7-af4e-fd211d8ed6f8@linux.alibaba.com/