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Shutemov" To: Ryan Roberts Cc: Andrew Morton , Matthew Wilcox , Yin Fengwei , David Hildenbrand , Yu Zhao , Yang Shi , "Huang, Ying" , Zi Yan , Nathan Chancellor , Alexander Gordeev , Gerald Schaefer , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 0/3] Optimize large folio interaction with deferred split Message-ID: <20230803120100.2glxdc4yf7sjn7h5@box.shutemov.name> References: <20230727141837.3386072-1-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: 68bpywt8p5km3ckkppd5cpb73r5nmhyi X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 569EDC0011 X-HE-Tag: 1691064068-314236 X-HE-Meta: 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 nmrueMyf XNQpJAi9+9CClVrmHoIfA/gYlUjZtbQQ2SwdyK2XK/gxOWEsp+w/0Mu+4wTvUlfVjupV8XWEG1iFWIPG2kSN5ykaW6jKhV5GE9TbWC1JCYnT636co4cmYWIbVm8kwY5b4xyI/1hwsiVe5nkY9aLvzDVxsk35PRIStT1k1a7fmD5EQZRONSIa1qCB+Uw== 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, Aug 02, 2023 at 05:42:23PM +0100, Ryan Roberts wrote: > - avoid the split lock contention by using mmu gather (suggested by Kirill) [Offlist] So, my idea is to embed struct deferred_split into struct mmu_gather and make zap path to use it instead of per-node/per-memcg deferred_split. This would avoid lock contention. If the list is not empty after zap, move the to the per-node/per-memcg deferred_split. But it is only relevant if we see lock contention. -- Kiryl Shutsemau / Kirill A. Shutemov