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[2003:cb:c74b:5500:e1f8:a310:8fa3:4ec1]) by smtp.gmail.com with ESMTPSA id c10-20020a19760a000000b00513a0876870sm153555lff.267.2024.04.05.03.42.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Apr 2024 03:42:38 -0700 (PDT) Message-ID: <6653ce52-53a2-4d91-b98f-50f1608ae59c@redhat.com> Date: Fri, 5 Apr 2024 12:42:35 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 5/6] mm: vmscan: Avoid split during shrink_folio_list() To: Ryan Roberts , Andrew Morton , Matthew Wilcox , Huang Ying , Gao Xiang , Yu Zhao , Yang Shi , Michal Hocko , Kefeng Wang , Barry Song <21cnbao@gmail.com>, Chris Li , Lance Yang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Barry Song References: <20240403114032.1162100-1-ryan.roberts@arm.com> <20240403114032.1162100-6-ryan.roberts@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: <20240403114032.1162100-6-ryan.roberts@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: 7bit X-Stat-Signature: qiyy4gwtmfg31ur6h8yqx4h133atfstx X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: B8F8B80005 X-Rspam-User: X-HE-Tag: 1712313762-459459 X-HE-Meta: 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 PimzyhkU 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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: On 03.04.24 13:40, Ryan Roberts wrote: > Now that swap supports storing all mTHP sizes, avoid splitting large > folios before swap-out. This benefits performance of the swap-out path > by eliding split_folio_to_list(), which is expensive, and also sets us > up for swapping in large folios in a future series. > > If the folio is partially mapped, we continue to split it since we want > to avoid the extra IO overhead and storage of writing out pages > uneccessarily. > > THP_SWPOUT and THP_SWPOUT_FALLBACK counters should continue to count > events only for PMD-mappable folios to avoid user confusion. THP_SWPOUT > already has the appropriate guard. Add a guard for THP_SWPOUT_FALLBACK. > It may be appropriate to add per-size counters in future. > > Reviewed-by: David Hildenbrand > Reviewed-by: Barry Song > Signed-off-by: Ryan Roberts > --- > mm/vmscan.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 00adaf1cb2c3..ffc4553c8615 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1223,11 +1223,12 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, > if (!can_split_folio(folio, NULL)) > goto activate_locked; > /* > - * Split folios without a PMD map right > - * away. Chances are some or all of the > - * tail pages can be freed without IO. > + * Split partially mapped folios right > + * away. We can free the unmapped pages > + * without IO. > */ > - if (!folio_entire_mapcount(folio) && > + if (data_race(!list_empty( > + &folio->_deferred_list)) && Please violate the 80 chars rule where reasonable. " Statements longer than 80 columns should be broken into sensible chunks, unless exceeding 80 columns significantly increases readability and does not hide information. " Likely some of that code here should be refactored into readable sub-functions. codingstyle also mentions "The answer to that is that if you need more than 3 levels of indentation, you're screwed anyway, and should fix your program." -- Cheers, David / dhildenb