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t=1675175171; bh=YgwryXO/WjU7qeBo+PfmZ5YImF9RsONUHj2VOYTQaLw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=HqKKuHdWWsetbObe+TJDLV7+/QOme9pRaZ4WnEZKgvpkSuCPam3bphp+UTceJN4nR uHqdAjCcB0JXZsEVxw+7X8vf5iFZggZBtIjIzu/Gq8PSjwBobBl/AY/tJzv/smjV/w wPn+zQviwMGzkf/jvRnwPzGvZlEXOIS5+K9NiniF1NgTbJJVSXKYwfVb6ek9hwP8Fp KiBkTJ/bgz+Tu54mX9uR7UICp9kIyaAc/qJ1pt5PmGh/p+LhFc+xlaAcblntK9PJuy XgI1PsqOG65uDWy85a9ORJrJS/mQlYJ3jiC6gPgpxBHnlBVDMgas/AGKqOzDW5xbyr +yAH6QW3uD5Hg== Message-ID: Date: Tue, 31 Jan 2023 16:26:06 +0200 MIME-Version: 1.0 Subject: Re: [PATCH] mm,page_alloc,cma: configurable CMA utilization Content-Language: en-US To: Sukadev Bhattiprolu , Andrew Morton Cc: Rik van Riel , Roman Gushchin , Vlastimil Babka , Joonsoo Kim , Minchan Kim , Chris Goldsworthy , Georgi Djakov , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230131071052.GB19285@hu-sbhattip-lv.qualcomm.com> From: Georgi Djakov In-Reply-To: <20230131071052.GB19285@hu-sbhattip-lv.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 62E69C001F X-Stat-Signature: 4t1qxy9tzco7jsbkukbru9damy1cbi9a X-HE-Tag: 1675175173-318909 X-HE-Meta: U2FsdGVkX1+7PJSWl+r9cUm5dWhe66v4Z+DTe9560K1sE5R9ZlKajsgBJzj2qBYYEbaMyC6AedvVRbCiIPlbv7oPy8DpRSCkzI10lrDq92f/auVCZRvYrZQ6CAhYIi6OWcjBysV2LEenzxBqi+nk14Wn+uEjpziO0ws9Rq8BMdqrzUaiv27vOqGqkyPZ0OBGvawIepxuEYJKAAe/0yI8ZF4dVfyau/s/2h2EJbrgYLnSpNQyladMFoRondRNAvf3OvddjqTfG8Eu0nlwWNf1PoREe+dFeAmuHjyIbf9AguYSAoK2lZpJgbIiprAyE6MBmyX1kg5cn5X5xvmqadNwWgnzaIpA5Nt0QVrAvEY2ws2BJvOMOMvtiC3GfNEsm6+nBlUAd3qkLsnCYaSRu3eOlwsZTuCZKJPeIqkCyRRs5X0P+y5nKVU9ETyKKqO1UtVOux0UPbM8O5w0K3rzstlIWNz9Yb8QWKtSSqVj7cPDf5Py2PT6WYQS/93Ge+gKvv8j7LDR/uqCM+6TMoj3NEM79bpDHpg3nYfLzXTGT1lG8gFfhPX5plecceLCtp3EScyW1fbgVwVYDSPT5Mk9Rj5JDUJy/lHpekM795hUw80MB4BXOwndnXVk06oSjc9sxaf9nFB4g024JVA8+2qFfU7psELnXYmkjNPL50VRIrhbjhaN0ol9fCB8qxLRHpdlskcUtZIooriQCUb3t+0UjSlDRCWQlagNtZJ36ui08/D7UQvX7ionzLeaCp3o25lfdDId4k2mv+KTNY4+kL5EVlJ7CZJ3K4jMqRGkIFFBOmB6/ukYAoUKCROQW6yo++d9JyNdDTyhUnY1zrNvpGZ5l87bYx2NOSbevFkq+c/Kod5lDLKwiWwulF9F4Y7dyYZCHk70OeIgAXiahtdPWdImQ0GFAntV7QRk8MzU1GGKkhv1UlJk1o8EJPDNbP0SJyCWGKfRx/1pyYOjbkLXqBCyRjW bHfC+02M ArlI47w5lB+Vag4KAXD9oh6r6W+Ch0VkifofA1PNWsKrMseanuGXv+MTMOWfCvDoyXjHyesymomUqnJRgm1yAqgFrqey1gJh/55E5wBme7wXsoV0uY/rvZwWhkSln86MlJTcEpgBIuTKtlQJ3oARso532/5q+PfT5b3Ds0KIo+JhYM5h+74p+Z7r4yysfEVGVvCs6bFVB6Rxd3VFqubu40w4W+ue4zVbfA6l68jy7f939t72WKJiVIlytgQDxviV8a6xsPq4n4CuvNBvd/EJ91GP31ZBt0icxFP0fvrtKb6bspUfSA7DuPxb/HTqq0g2Eo8uI0tDhkTwJ0O5VlJeTaBh4YzGl3+B0RDVRAY8tm1lkl6RzFKDBOXbUlqfjmlwepDfE/b6QqmlSi2+E1navoElalSIm0qrzZe1QYLcbJy3YfjGodVXC2j9K4OnKMKvsLRZJY58KMlN/UAcZST3uHNMVRA== 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: Hi Sukadev, On 31.01.23 9:10, Sukadev Bhattiprolu wrote: > > Commit 16867664936e ("mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations") > added support to use CMA pages when more than 50% of total free pages in > the zone are free CMA pages. > > However, with multiplatform kernels a single binary is used across different > targets of varying memory sizes. A low memory target using one such kernel > would incur allocation failures even when sufficient memory is available in > the CMA region. On these targets we would want to utilize a higher percentage > of the CMA region and reduce the allocation failures, even if it means that a > subsequent cma_alloc() would take longer. > > Make the percentage of CMA utilization a configurable parameter to allow > for such usecases. The above makes sense to me. But it also needs to documented like the other sysctl files in Documentation/admin-guide/sysctl/vm.rst Thanks, Georgi > > Signed-off-by: Sukadev Bhattiprolu > --- > Note: There was a mention about it being the last resort to making this > percentage configurable (https://lkml.org/lkml/2020/3/12/751). But > as explained above, multi-platform kernels for varying memory size > targets would need this to be configurable. > --- > include/linux/mm.h | 1 + > kernel/sysctl.c | 8 ++++++++ > mm/page_alloc.c | 18 +++++++++++++++--- > mm/util.c | 2 ++ > 4 files changed, 26 insertions(+), 3 deletions(-) >