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[2003:cb:c71c:4e00:b097:7075:f6ba:300a]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-429059a8912sm120876935e9.38.2024.08.09.02.19.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Aug 2024 02:19:14 -0700 (PDT) Message-ID: <99b78488-c524-4269-b1fb-a13eaa4f274c@redhat.com> Date: Fri, 9 Aug 2024 11:19:13 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: Override mTHP "enabled" defaults at kernel cmdline To: Ryan Roberts , Andrew Morton , Jonathan Corbet , Barry Song , Lance Yang , Baolin Wang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240808101700.571701-1-ryan.roberts@arm.com> From: David Hildenbrand Content-Language: en-US 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: <20240808101700.571701-1-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 08.08.24 12:16, Ryan Roberts wrote: > Add thp_anon= cmdline parameter to allow specifying the default > enablement of each supported anon THP size. The parameter accepts the > following format and can be provided multiple times to configure each > size: > > thp_anon=[KMG]: > > See Documentation/admin-guide/mm/transhuge.rst for more details. > > Configuring the defaults at boot time is useful to allow early user > space to take advantage of mTHP before its been configured through > sysfs. I suspect a khugeapged enhancement and/or kernel-config-dependant defaults and/or early system settings will also be able to mitigate that without getting kernel cmdlines involved in the future. > > Signed-off-by: Ryan Roberts > --- > > Hi All, > > I've split this off from my RFC at [1] because Barry highlighted that he would > benefit from it immediately [2]. There are no changes vs the version in that > series. > > It applies against today's mm-unstable (275d686abcb59). (although I had to fix a > minor build bug in stackdepot.c due to MIN() not being defined in this tree). > > Thanks, > Ryan > > > .../admin-guide/kernel-parameters.txt | 8 +++ > Documentation/admin-guide/mm/transhuge.rst | 26 +++++++-- > mm/huge_memory.c | 55 ++++++++++++++++++- > 3 files changed, 82 insertions(+), 7 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index bcdee8984e1f0..5c79b58c108ec 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6631,6 +6631,14 @@ > : poll all this frequency > 0: no polling (default) > > + thp_anon= [KNL] > + Format: [KMG]:always|madvise|never|inherit > + Can be used to control the default behavior of the > + system with respect to anonymous transparent hugepages. > + Can be used multiple times for multiple anon THP sizes. > + See Documentation/admin-guide/mm/transhuge.rst for more > + details. > + > threadirqs [KNL,EARLY] > Force threading of all interrupt handlers except those > marked explicitly IRQF_NO_THREAD. > diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst > index 24eec1c03ad88..f63b0717366c6 100644 > --- a/Documentation/admin-guide/mm/transhuge.rst > +++ b/Documentation/admin-guide/mm/transhuge.rst > @@ -284,13 +284,27 @@ that THP is shared. Exceeding the number would block the collapse:: > > A higher value may increase memory footprint for some workloads. > > -Boot parameter > -============== > +Boot parameters > +=============== > > -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. Wondering if a syntax like thp_anon=16K,32K,64K:always;1048K,2048K:madvise (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 ;) -- Cheers, David / dhildenb