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[149.14.88.26]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-458953b3471sm19091135e9.30.2025.07.30.02.33.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Jul 2025 02:33:52 -0700 (PDT) Message-ID: Date: Wed, 30 Jul 2025 11:33:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH resend v2] /dev/zero: try to align PMD_SIZE for private mapping To: Zhang Qilong , arnd@arndb.de, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, wangkefeng.wang@huawei.com, sunnanyong@huawei.com References: <20250730091905.383353-1-zhangqilong3@huawei.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/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: <20250730091905.383353-1-zhangqilong3@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: FucFi2HjGyBAZsgEMN0k6nw2OeXItq50IQhP3o3Wabk_1753868034 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 084E3180008 X-Stat-Signature: gz1cfur333686aar8d85c71t8a47u9zh X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1753868036-164405 X-HE-Meta: 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 aFXtxZi9 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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 30.07.25 11:19, Zhang Qilong wrote: > Attempt to map aligned to huge page size for private mapping which > could achieve performance gains, the mprot_tw4m in libMicro average > execution time on arm64: > - Test case: mprot_tw4m > - Before the patch: 22 us > - After the patch: 17 us > > Signed-off-by: Zhang Qilong > --- > v2: > - Add comments on code suggested by Lorenzo > - Use IS_ENABLED to check THP config > > drivers/char/mem.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/char/mem.c b/drivers/char/mem.c > index 48839958b0b1..c27cc89bd02d 100644 > --- a/drivers/char/mem.c > +++ b/drivers/char/mem.c > @@ -525,11 +525,18 @@ static unsigned long get_unmapped_area_zero(struct file *file, > * so as not to confuse shmem with our handle on "/dev/zero". > */ > return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); > } > > - /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */ > + /* > + * Otherwise flags & MAP_PRIVATE: with no shmem object beneath it, > + * attempt to map aligned to huge page size if possible, otherwise we > + * fall back to system page size mappings. > + */ > + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > + return thp_get_unmapped_area(file, addr, len, pgoff, flags); > + > return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags); > #else > return -ENOSYS; > #endif > } Acked-by: David Hildenbrand -- Cheers, David / dhildenb