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Wed, 7 Jul 2021 09:32:33 +0000 Subject: Re: page pools, was Re: [PATCH v9 1/5] drm: Add a sharable drm page-pool implementation To: Christoph Hellwig Cc: John Stultz , lkml , Daniel Vetter , Sumit Semwal , Liam Mark , Chris Goldsworthy , Laura Abbott , Brian Starkey , Hridya Valsaraju , Suren Baghdasaryan , Sandeep Patil , Daniel Mentz , ??rjan Eide , Robin Murphy , Ezequiel Garcia , Simon Ser , James Jones , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, Mel Gorman , linux-mm@kvack.org References: <20210630013421.735092-1-john.stultz@linaro.org> <20210630013421.735092-2-john.stultz@linaro.org> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <84a2ab1d-e76f-2cd3-39bc-6937586d7e47@amd.com> Date: Wed, 7 Jul 2021 11:32:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: FR0P281CA0046.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:48::23) To MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2a02:908:1252:fb60:7671:3328:2129:96b5] (2a02:908:1252:fb60:7671:3328:2129:96b5) by FR0P281CA0046.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:48::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.8 via Frontend Transport; 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See the numbers John provided in the cover letter. >> >> But essentially at least I would be totally fine moving this into the page >> allocator, but moving it outside of TTM already helps with this goal. So >> this patch set is certainly a step into the right direction. > Unless I'm badly misreading the patch and this series there is nothing > about cache attributes in this code. It just allocates pages, zeroes > them, eventually hands them out to a consumer and registers a shrinker > for its freelist. > > If OTOH it actually dealt with cachability that should be documented > in the commit log and probably also the naming of the implementation. Mhm, good point. In this case all left is the clearing overhead from the allocation hot path to the free path and I'm not really sure why the core page allocator shouldn't do that as well. Regards, Christian.