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[2003:d8:2f09:3f00:d228:bd67:7baa:d604]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4290c7728c5sm76115605e9.32.2024.08.09.06.15.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Aug 2024 06:15:47 -0700 (PDT) Message-ID: <8258bf4c-ecec-4e06-ada0-da9fb99b1219@redhat.com> Date: Fri, 9 Aug 2024 15:15:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: Override mTHP "enabled" defaults at kernel cmdline To: Ryan Roberts , Barry Song Cc: Andrew Morton , Jonathan Corbet , Lance Yang , Baolin Wang , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240808101700.571701-1-ryan.roberts@arm.com> <99b78488-c524-4269-b1fb-a13eaa4f274c@redhat.com> <75eb6e75-8a6d-460a-8e96-7496ed1396b7@redhat.com> <3c8f00ea-af28-46c7-9a5d-83c4b9462be3@arm.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: <3c8f00ea-af28-46c7-9a5d-83c4b9462be3@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 3AC2D140024 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: zfxgznap66qkzojup3dswk4fasyn7psh X-HE-Tag: 1723209352-837170 X-HE-Meta: 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 ae5KY8ym 3hugutIgjkWqEJvS/fG3BP2+37sX8fcgcSEdYnPE2pDTkcK9WTHmlQfENt3kuV+jANU6XGZLII9nNJXcu9VR+JkqLLghMyK5XZI6hVkWjoLg50Rt6wq8DPUTTY6bfQoj/F+MkpYEenGtkjFeTyCnh0eWxsMrDZqdsMPLAJkTuGqR27jSk8ic5ckeUeSZDbUN6Ol26jw/TFQOCP+BPgKbzhzmVlGbCjfuuiHgVwKbayT6xi2ZXPhRyUE/hurjaUZC+TnqoAdv5c8BOFb/FDzwhtt7Uy3iRZk+2XuID2fux7JI5mhiCMgZ6RKUu4+AfOBgVVJfHW+Y5TFLvRQbHZ1i1jTwSdX7RBJSYx3eSEvzf4SCCQlwclehIC2A4vTSo3mRpfJRP4Fb6p5mEhqWug9ttStIq8zQwcDAgFldeFTHA9q6PdcRfmmx/VCr0l7TskkJ2Ca8fIuEWuPzqikkVQgc3xLsaki1L74qKN0A2 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: >>>>> -You can change the sysfs boot time defaults of Transparent Hugepage >>>>> -Support by passing the parameter ``transparent_hugepage=always`` or >>>>> -``transparent_hugepage=madvise`` or ``transparent_hugepage=never`` >>>>> -to the kernel command line. >>>>> +You can change the sysfs boot time default for the top-level "enabled" >>>>> +control by passing the parameter ``transparent_hugepage=always`` or >>>>> +``transparent_hugepage=madvise`` or ``transparent_hugepage=never`` to the >>>>> +kernel command line. >>>>> + >>>>> +Alternatively, each supported anonymous THP size can be controlled by >>>>> +passing ``thp_anon=[KMG]:``, where ```` is the THP size >>>>> +and ```` is one of ``always``, ``madvise``, ``never`` or >>>>> +``inherit``. >>>>> + >>>>> +For example, the following will set 64K THP to ``always``:: >>>>> + >>>>> +     thp_anon=64K:always >>>>> + >>>>> +``thp_anon=`` may be specified multiple times to configure all THP sizes as >>>>> +required. If ``thp_anon=`` is specified at least once, any anon THP sizes >>>>> +not explicitly configured on the command line are implicitly set to >>>>> +``never``. >>>> >>>> I suggest documenting that "thp_anon=" will not effect the value of >>>> "transparent_hugepage=", or any configured default. > > Did you see the previous conversation with Barry about whether or not to honour > configured defaults when any thp_anon= is provided [1]? Sounds like you also > think we should honour the PMD "inherit" default if not explicitly provided on > the command line? (see link for justification for the approach I'm currently > taking). I primarily think that we should document it :) What if someone passes "transparent_hugepage=always" and "thp_anon=..."? I would assume that transparent_hugepage would only affect the global toggle then? > > [1] > https://lore.kernel.org/linux-mm/CAGsJ_4x8ruPspuk_FQVggJMWcXLbRuZFq44gg-Dt7Ewt3ExqTw@mail.gmail.com/ > >>>> >>>> Wondering if a syntax like >>>> >>>> thp_anon=16K,32K,64K:always;1048K,2048K:madvise > > Are there examples of that syntax already or have you just made it up? I found > examples with the colon (:) but nothing this fancy. I guess that's not a reason > not to do it though (other than the risk of screwing up the parser in a subtle way). I made it up -- mostly ;) I think we are quite flexible on what we can do. As always, maybe we can keep it bit consistent with existing stuff. For hugetlb_cma we have things like ":nn[KMGTPE|[,:nn[KMGTPE]] "memmap=" options are more ... advanced, including memory ranges. There are a bunch more documented in kernel-parameters.txt that have more elaborate formats. Ranges would probably be the most valuable addition. So maybe we should start with: thp_anon=16K-64K:always,1048K-2048K:madvise So to enable all THPs it would simply be thp_anon=16K-2M:always Interesting question what would happen if someone passes: thp_anon=8K-2M:always Likely we simply would apply it to any size in the range, even if start/end is not a THP size. But we would want to complain to the user if someone only specifies a single one (or a range does not even select a single one) that does not exist: thp_anon=8K:always > >>>> >>>> (one could also support ranges, like "16K-64K") >>>> >>>> Would be even better. Then, maybe only allow a single instance. >>>> >>>> Maybe consider it if it's not too crazy to parse ;) > I'll take a look. I'm going to be out for 3 weeks from end of Monday though, so Oh, lucky you! Enjoy! > probably won't get around to that until I'm back. I know Barry is keen to get > this merged, so Barry, if you'd like to take it over that's fine by me (I'm sure > you have enough on your plate though). -- Cheers, David / dhildenb