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d=linux-foundation.org; s=korg; t=1691686492; bh=/BiI3r6KjM3Bn3xX0qfnb30NGMBPvBrMysulwCHjixw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DOci+ZnrHilJyVQKb9f/WNY+b7IOlSolnLUO/FJnPlUjvkIE0EcrUcE4ycihUAART u9QmNZkNXDnsBCtGYF5DFGL4BVXfpMcuI3NAYR7leVOzQlKwEPBecn81/QThWECi2c +TJGjB0gU7CPqq6LVz6eYytYOlCRYvOqN3sHfJIE= Date: Thu, 10 Aug 2023 09:54:51 -0700 From: Andrew Morton To: Bibek Kumar Patro Cc: , , , Subject: Re: [PATCH v2] cma: introduce CMA_ALLOC_DEBUG config Message-Id: <20230810095451.cada824810441ecc955e2b2e@linux-foundation.org> In-Reply-To: <20230809131640.18791-1-quic_bibekkum@quicinc.com> References: <20230809131640.18791-1-quic_bibekkum@quicinc.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: efqnurfowezhmt9oeiqu6jhfqmu3s71e X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4F6C62001B X-HE-Tag: 1691686494-968271 X-HE-Meta: U2FsdGVkX1/fd4rVI7EL6rAeUTmy9gPT4DWu7Hf14ETo+ueg2rQ8by0eDCTcNAEjT7H6ZaBF3fN4tGTyKpoeO9AeMBe1qJAQneIBeq+WAmtMedijGBvgHK9IyIHJcaSGzsSIuITT2YcZDp7FicYuCJlhf0UDadIhd0QPzkyTSp0tRBUou56lLqPKVp8t9Zn1vBf2ItnWDdX0SfDhrAoGNrsUqNS2/ISPI0iGGww/F6VtMWl2yngbMAmMWxjclV/MtC5tEo+huvKgvmye3t9Ij/bKYikufzjVMzARcNQHjMwP75KGVxSMH4V/h0kza4masL0QBw/sE9AJ4PybZsSXuCDl348nRqcWq3PagE7udP2Q4K2+w3Ll3uemU+euB+XTVtVVWcBlr/cBCxIkPx8VOMiR5hYlzFQ6JBe9ZPbpjaNECY5IChoqwK+BCMX0CdRiEjofx+gCxIGJghkDcQo5pSJ97KjERFwhbUh8RS/Xnjj9pjrnXe4IXcOwfhv3Sl5MCNVxGPidh/lqRBtP2Dw9ARh3u7e4o0XN20gwbznhCjw+nPwGP5BWR2+IZj+C6fWM6u3fiuHIIw80eGds6V1FRs1TAo49AVNegwWX+lsP4R70Li2e2iptq0cZxpNmRhfwggSf10U3f00eLk/jltAZQLimcS6ZZV5ZhV04oaLu9zrxBgudkpIB9KG5qnUelGUQh6I9+c5O7FEBUrmjxqXsYFui4toszxhloCzqCrWIetmHxzMjjksAXfLHiV2W2rv3Ts8yA1rtP0WJcWnI9UaUeTmWX58vVq1ZkJ8RWI2YONd5JM8xBWZPv5w4IPkEnyly93ee/LMqMXkUweJwCu0bonVUbf4BZDn0Oz/y2KJIMrpuDxUBnjQbZ9fPociJ4O3AjV5DZ9yi+X0R+ThYCn+RnhcwsQuFaBbO314lxSYbAMCY7Vcda58CHyjkJktQz4gwnK6umPhZyKSC8N9DOYt NnZ+g7dx l2XQaidw27psr8Wi90JT3fVdBe+OWI65F14OLxRETe0ZdjZh8GC+YVRymkhpX7ISSdHLjPTVaGgl2Uwcd4tF8lF7fVXKmHnRr1cKtHDqPrQUYCQa3O4YFZ6kNAjL6t22iO25dCFzxbMg+sYYtOiRXrHC8GXI4X1/YCkNxF86cZizq2ZpCiTP/SOtXmtGzVYuVHEF+beRanpgTIH6SmG3lL8uDwNXqc3gzqdE3dsti1zDkZb7JAg1mrRHhLk8rIpCp9eA6Hcu1b+73xllkIFQTO0sqvMRL4ReSd+th7wsKJetfl1gGiNT2RitgLVyzh9xqQuUZh6QhECRW/uOrVE4mDxx36VmNIgPPSfUngdIm04YDW0REakp5V7ul2xAg99WEVhxjP94/t25RSo/fJAUMPC2+zNiS5JinDx4ArM/groUCj7a6h9oymidBrw== 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: On Wed, 9 Aug 2023 18:46:40 +0530 Bibek Kumar Patro wrote: > Currently enabling CONFIG_CMA_DEBUG enables DEBUG preprocessor macro. > If DEBUG is defined, it's equivalent to a printk with KERN_DEBUG loglevel > flooding the dmesg buffer with pr_debug prints from mm/cma driver and from > included files as well. This results in excessive amount of CMA logging and > also might distract the debug teams with unrelated KERN_DEBUG prints.One of > the ways engineers currently tackle this problem is by passing loglevel=N > though commandline to suppress KERN_DEBUG messages. This approach can > sometimes become tiresome due to its repetitive nature. > This patch proposes an alternative approach by introducing a simple new > config CONFIG_CMA_ALLOC_DEBUG which only shows the cma bit allocation > status in case of cma failure and do not enable DEBUG preprocessor macro > from CONFIG_CMA_DEBUG avoiding excessive CMA logging from pr_debug. > Engineers and tech teams seeking only for bitmap status in case of cma > failure can use this simple config instead of worrying about changing > the loglevel or trying other similar workarounds. Would it be better to control this at runtime? With a /proc or /sys tunable?