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[91.12.101.227]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-395c7df34eesm18336971f8f.18.2025.03.18.06.02.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Mar 2025 06:02:22 -0700 (PDT) Message-ID: <24ca760c-a861-4797-a434-d91a59513b12@redhat.com> Date: Tue, 18 Mar 2025 14:02:21 +0100 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/cma: using per-CMA locks to improve concurrent allocation performance To: Andrew Morton , yangge1116@126.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, 21cnbao@gmail.com, baolin.wang@linux.alibaba.com, aisheng.dong@nxp.com, liuzixing@hygon.cn References: <1739152566-744-1-git-send-email-yangge1116@126.com> <20250317204325.99b45373023ad2f901c1152e@linux-foundation.org> 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: <20250317204325.99b45373023ad2f901c1152e@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 18.03.25 04:43, Andrew Morton wrote: > On Mon, 10 Feb 2025 09:56:06 +0800 yangge1116@126.com wrote: > >> From: yangge >> >> For different CMAs, concurrent allocation of CMA memory ideally should not >> require synchronization using locks. Currently, a global cma_mutex lock is >> employed to synchronize all CMA allocations, which can impact the >> performance of concurrent allocations across different CMAs. >> >> To test the performance impact, follow these steps: >> 1. Boot the kernel with the command line argument hugetlb_cma=30G to >> allocate a 30GB CMA area specifically for huge page allocations. (note: >> on my machine, which has 3 nodes, each node is initialized with 10G of >> CMA) >> 2. Use the dd command with parameters if=/dev/zero of=/dev/shm/file bs=1G >> count=30 to fully utilize the CMA area by writing zeroes to a file in >> /dev/shm. >> 3. Open three terminals and execute the following commands simultaneously: >> (Note: Each of these commands attempts to allocate 10GB [2621440 * 4KB >> pages] of CMA memory.) >> On Terminal 1: time echo 2621440 > /sys/kernel/debug/cma/hugetlb1/alloc >> On Terminal 2: time echo 2621440 > /sys/kernel/debug/cma/hugetlb2/alloc >> On Terminal 3: time echo 2621440 > /sys/kernel/debug/cma/hugetlb3/alloc >> >> We attempt to allocate pages through the CMA debug interface and use the >> time command to measure the duration of each allocation. >> Performance comparison: >> Without this patch With this patch >> Terminal1 ~7s ~7s >> Terminal2 ~14s ~8s >> Terminal3 ~21s ~7s >> >> To slove problem above, we could use per-CMA locks to improve concurrent >> allocation performance. This would allow each CMA to be managed >> independently, reducing the need for a global lock and thus improving >> scalability and performance. > > This patch was in and out of mm-unstable for a while, as Frank's series > "hugetlb/CMA improvements for large systems" was being added and > dropped. > > Consequently it hasn't received any testing for a while. > > Below is the version which I've now re-added to mm-unstable. Can > you please check this and retest it? > > Thanks. > > From: Ge Yang > Subject: mm/cma: using per-CMA locks to improve concurrent allocation performance > Date: Mon, 10 Feb 2025 09:56:06 +0800 > > For different CMAs, concurrent allocation of CMA memory ideally should not > require synchronization using locks. Currently, a global cma_mutex lock > is employed to synchronize all CMA allocations, which can impact the > performance of concurrent allocations across different CMAs. > > To test the performance impact, follow these steps: > 1. Boot the kernel with the command line argument hugetlb_cma=30G to > allocate a 30GB CMA area specifically for huge page allocations. (note: > on my machine, which has 3 nodes, each node is initialized with 10G of > CMA) > 2. Use the dd command with parameters if=/dev/zero of=/dev/shm/file bs=1G > count=30 to fully utilize the CMA area by writing zeroes to a file in > /dev/shm. > 3. Open three terminals and execute the following commands simultaneously: > (Note: Each of these commands attempts to allocate 10GB [2621440 * 4KB > pages] of CMA memory.) > On Terminal 1: time echo 2621440 > /sys/kernel/debug/cma/hugetlb1/alloc > On Terminal 2: time echo 2621440 > /sys/kernel/debug/cma/hugetlb2/alloc > On Terminal 3: time echo 2621440 > /sys/kernel/debug/cma/hugetlb3/alloc > > We attempt to allocate pages through the CMA debug interface and use the > time command to measure the duration of each allocation. > Performance comparison: > Without this patch With this patch > Terminal1 ~7s ~7s > Terminal2 ~14s ~8s > Terminal3 ~21s ~7s > > To solve problem above, we could use per-CMA locks to improve concurrent > allocation performance. This would allow each CMA to be managed > independently, reducing the need for a global lock and thus improving > scalability and performance. > > Link: https://lkml.kernel.org/r/1739152566-744-1-git-send-email-yangge1116@126.com > Signed-off-by: Ge Yang > Reviewed-by: Barry Song > Acked-by: David Hildenbrand > Reviewed-by: Oscar Salvador > Cc: Aisheng Dong > Cc: Baolin Wang > Signed-off-by: Andrew Morton Acked-by: David Hildenbrand -- Cheers, David / dhildenb