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Fri, 21 Aug 2020 16:45:44 +0900 (KST) Received: from KEI (unknown [12.36.155.227]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20200821074544epsmtip1e7d25fed313408de35eeeb6dd2b14396~tONheg87B0588805888epsmtip1C; Fri, 21 Aug 2020 07:45:44 +0000 (GMT) Date: Fri, 21 Aug 2020 16:38:13 +0900 From: Cho KyongHo To: Brian Starkey Cc: Hyesoo Yu , sumit.semwal@linaro.org, minchan@kernel.org, akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, joaodias@google.com, linux-mm@kvack.org, surenb@google.com, vbabka@suse.cz, afd@ti.com, benjamin.gaignard@linaro.org, lmark@codeaurora.org, labbott@redhat.com, john.stultz@linaro.org, christian.koenig@amd.com, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, devicetree@vger.kernel.org, nd@arm.com Subject: Re: [PATCH 0/3] Chunk Heap Support on DMA-HEAP Message-ID: <20200821073813.GA190335@KEI> MIME-Version: 1.0 In-Reply-To: <20200819132204.2rki3xsczdy2cpsk@DESKTOP-E1NTVVP.localdomain> User-Agent: Mutt/1.5.24 (2015-08-30) X-Brightmail-Tracker: H4sIAAAAAAAAA01Te0xTZxTfd9veXsgqlwL6haFiJ1sg41FY4UOEgYq529SxLO6VzdLADRBL aXqpGzgzZPKWIgI63jU8lAKDIAqjAqEwHh0qQQREGBE2DYTHAshgBreWCwn//c45v9/3+845 OQRHWMy3J6IUsbRKIZOLcEvu3U5n5Fp1/gOph67FCS0as/moqK4GR4kGI46mjAMAzU/qeai0 6wEPDb1cxNFG2gAPVWX8hKN/tFMc1P/KFVXdW8PQytAzDD1qKcLR5fo7PPRHzX88VNA3jKHK l4t81H/zMgcltXbxkXFimY9yBrU4KryoAYF7qKTBDZyqKakB1CNNJkZpG9RUgy4NpxqWrvKp 9PkhjBofvodTvT+/4lKTGT0Y9fT1NIdabHuMU5pGHaD6tV18qme0CaOWG/aFkF/LD0fSsnBa 5UgrwmLCoxQR/qKPP5MelUq8PcSuYl/kI3JUyKJpf9GxEyGux6PkplmIHM/J5GpTKkTGMCL3 gMOqGHUs7RgZw8T6i2hluFwpFivdGFk0o1ZEuIXFRB8Se3h4SkzMUHlk6ugGX7kk/P7WUgU3 ATRZpQMLApLvwycvyrB0YEkIyWYAE/Pb+GywBGBt329bwSqAo0n/gm2JRn97q9AK4HxzCZcN ngFYfv8az8zikk6wvGQVN2OcdIHVxT0mNUHYks7wYpHUzOeQxVw4l5KxybEhfWCnLpVr5ghM nF8mBea0gLSGffl/cs3YgvwI6q9l4WaKHXkQznb8aH4Gku0WMDtnjcN+7hgcbqvlsdgGzvY0 8llsD2eykvms4DqAC6UGnC3cBnBVb81iL1jwPGWzSw4ZCbsHczCzGSTfhl1jXDa9C6Z2bvDZ tACmJgtZ5UH4a94wd9tK0zq6hSlYcVfDY8dTg8FLZXO8K2B/wY7WCna4sfg9qNUv4QUmCw75 Frz5mmChM6xrcdcCng7sppVMdATNeCrFO5fdADbvxCW4GeTM/+1mABgBDAASHJGtILPVTyoU hMvi4mlVjFSlltOMAUhMa8rm2NuFxZgOTRErFUs8vb09fCVI4u2JRHsE0QcGzgjJCFksfZam lbRqW4cRFvYJWJ5dn/xAfmZ9deu3Q76rhu96ix6c2js/E7kiCArYP/fGobjizwPWT/nnVXBp m6npvybL1CXBtX0CqxMOT9sCx9Mmc72CA6Fi+ozFw/Pvjlc16Y8Y1erO5+33dYMLdz4sP854 iQNz176qS5OIT3a0/x5lXbnmfiGv4MuxNxPDP/U/qRvsz9/tGecX7l8/rVlxPXphtvt0B1E6 F+qdLG3IbbKta6zMtpy4cmu50GNkvXfi9NQnX8zoQquXnfo6LPbm3HhYHyrzexG/z2FlrOwq HmQsW11/pzqeWJgK9u52OCdIuEGctWJw3ohGaW/zjadPzUjKrowsovDxDzmW80F65lLIkyMi LhMpE7twVIzsf1gBG/OwBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA02Sf0yMcRzHfZ/nued5OjseyfqqiZ7F1Cpuk75+xabNwzSxWTujc6tHP9xV 7oRiU9GorqSUOidno3Idcghd2F1HOs2sYrf8OPnValqUKKn01Iz/Xnt/Xu/3Xx8ad39HeNEJ Sft5dZJCyZJioq6R9QmqPrxWvvRh9nLU5zhNIf11E4mybA4SvXc8B6jXZRGhC/ZnItQ+2Eei 0ZznInQl7xiJfhre46hlJAhdaRjC0Pf2Tgy11etJpK29LUJvTeMipGt+iaHKwT4KtVRpcZR9 304hx5sBChW3Gkh0LrMArPPksltHSc5UYQJcW0E+xhnMqZzZmENy5v4iisvtbce41y8bSO5J 2QjBufKaMO7V2Aec63vwguQKbhkB12KwU1yT8w7GDZh9Ipkd4tWxvDLhAK9eErZbHN/s+Iml mJlDbZmfyQxQKMkFbjRklsECy01KYHfGAmDzucip3AtW5F3Fpng2dB23i3KBeMJxAfijtgMX DgSzEF6q+EEKTDIBsOZ8E8gFNO3B+MNMvVzwceYiAV/oKied2UwobDSeJARHMuFcc0mmNk0Y 7LpUM7kpYWbB5vKPhMD4xKZzrBsTfJzxhlVjtBC7MZugpfQUKcRzGD/YYz1aCGbp/ivr/ivr /pUNADeCuXyKRhWn0khTpEn8wWCNQqVJTYoLjklWmcHkEwT43wV3jF+DbQCjgQ1AGmc9JPn3 V8ndJbGKtHRenSxXpyp5jQ140wTrKXHuuxjtzsQp9vN7eT6FV/+9YrSbVwZWFvj4fPL23vBR W9uDs7Kz25nH+W+2he/qt2rWKRuz6o64pCt03e07V/scKg9B+YG1T7Xf/EJkUcOvzevrq0+Y ykN9LUGlK6OKD6RFlLutvVd1kx3uN12IXhzztORGooQdkKVGjBTN1cqjcuxWQ7f/2y+JnmHK kMxf4RtfZS1QyddE1E3TF40n7OmZFk/clc0s+VQzf1mOWDTjcuSQXGtM5zNOKaS+Z8KcyfhY ybZs+CiveOvp6MSunobWWKMqyC9t6cnxORmbNwR0BCr1gfX70tlha2EXvjg6y8s3Zjp10KPT uah6xWDHFkoWgd36tL6ya2D8UdmCnpn4PMPVYiv7myU08QppAK7WKP4A2KcPc3MDAAA= X-CMS-MailID: 20200821074545epcas2p23109c52bfe76a58b26ba1f509cb86165 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----lWUYs60uNheWdrlwd5Sxb-jVEnyT8vPvqGqUNsoxLEsY2Otg=_4f1bd_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20200818074547epcas2p21e0c2442873d03800c7bc2c3e76405d6 References: <20200818080415.7531-1-hyesoo.yu@samsung.com> <20200818105557.svky5c7gdvk6khzu@DESKTOP-E1NTVVP.localdomain> <20200819034626.GB70898@KEI> <20200819132204.2rki3xsczdy2cpsk@DESKTOP-E1NTVVP.localdomain> X-Rspamd-Queue-Id: 697CB16A0AE X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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: ------lWUYs60uNheWdrlwd5Sxb-jVEnyT8vPvqGqUNsoxLEsY2Otg=_4f1bd_ Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Hi Brain, On Wed, Aug 19, 2020 at 02:22:04PM +0100, Brian Starkey wrote: > Hi KyongHo, > > On Wed, Aug 19, 2020 at 12:46:26PM +0900, Cho KyongHo wrote: > > I have seriously considered CPA in our product but we developed our own > > because of the pool in CPA. > > Oh good, I'm glad you considered it :-) > > > The high-order pages are required by some specific users like Netflix > > app. Moreover required number of bytes are dramatically increasing > > because of high resolution videos and displays in these days. > > > > Gathering lots of free high-order pages in the background during > > run-time means reserving that amount of pages from the entier available > > system memory. Moreover the gathered pages are soon reclaimed whenever > > the system is sufferring from memory pressure (i.e. camera recording, > > heavy games). > > Aren't these two things in contradiction? If they're easily reclaimed > then they aren't "reserved" in any detrimental way. And if you don't > want them to be reclaimed, then you need them to be reserved... > > The approach you have here assigns the chunk of memory as a reserved > CMA region which the kernel is going to try not to use too - similar > to the CPA pool. > > I suppose it's a balance depending on how much you're willing to wait > for migration on the allocation path. CPA has the potential to get you > faster allocations, but the downside is you need to make it a little > more "greedy". > I understand why you think it as contradiction. But I don't think so. Kernel page allocator now prefers free pages in CMA when allocating movable pages by commit https://lore.kernel.org/linux-mm/CAAmzW4P6+3O_RLvgy_QOKD4iXw+Hk3HE7Toc4Ky7kvQbCozCeA@mail.gmail.com/ . We are trying to reduce unused pages to improve performance. So, unused pages in a pool should be easily reclaimed. That is why we does not secure free pages in a special pool for a specific usecase. Instead we have tried to reduce performance bottle-necks in page migration to allocate large amount memory when the memory is needed. ------lWUYs60uNheWdrlwd5Sxb-jVEnyT8vPvqGqUNsoxLEsY2Otg=_4f1bd_ Content-Type: text/plain; charset="utf-8" ------lWUYs60uNheWdrlwd5Sxb-jVEnyT8vPvqGqUNsoxLEsY2Otg=_4f1bd_--