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[73.69.118.222]) by smtp.gmail.com with ESMTPSA id q4sm4817170qkj.5.2021.01.28.16.17.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Jan 2021 16:17:41 -0800 (PST) Subject: Re: Re: [PATCH 0/1] arm64/sparsemem: reduce SECTION_SIZE_BITS To: Will Deacon , Catalin Marinas , linux-kernel@vger.kernel.org, Anshuman Khandual , linux-arm-kernel@lists.infradead.org, Sudarshan Rajagopalan , David Hildenbrand , linux-mm@kvack.org Cc: kernel-team@android.com References: <161125239746.2653965.4342337503570976678.b4-ty@kernel.org> From: Pavel Tatashin Message-ID: <2489ef84-dd4d-b659-a61b-38582d168316@soleen.com> Date: Thu, 28 Jan 2021 19:17:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <161125239746.2653965.4342337503570976678.b4-ty@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 1/21/21 1:26 PM, Will Deacon wrote: > On Wed, 20 Jan 2021 21:29:12 -0800, Sudarshan Rajagopalan wrote: >> This patch is the follow-up from the discussions in the thread [1]. >> Reducing the section size has the merit of reducing wastage of reserved memory >> for vmmemmap mappings for sections with large memory holes. Also with smaller >> section size gives more grunularity and agility for memory hot(un)plugging. >> >> But there are also constraints in reducing SECTION_SIZE_BIT: >> >> [...] > > Applied to arm64 (for-next/misc), thanks! We have been using 128M for 4K pages for a while, using patch [1] without issues. One thing that needs to be also modified is makedumpfile [2]- line 76, must update it SECTIONS_SIZE_BITS based on the PAGESIZE. [1] https://lore.kernel.org/lkml/20190423203843.2898-1-pasha.tatashin@soleen.com/ [2] https://sourceforge.net/p/makedumpfile/code/ci/master/tree/arch/arm64.c > > [1/1] arm64/sparsemem: reduce SECTION_SIZE_BITS > https://git.kernel.org/arm64/c/f0b13ee23241 > > Cheers, >