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Thu, 18 Dec 2025 21:31:48 -0800 (PST) Received: from localhost.localdomain ([114.231.217.195]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7ff7e0a19d8sm1033784b3a.42.2025.12.18.21.31.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Dec 2025 21:31:48 -0800 (PST) Date: Fri, 19 Dec 2025 13:31:23 +0800 From: Vernon Yang To: "David Hildenbrand (Red Hat)" Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang Subject: Re: [PATCH 4/4] mm: khugepaged: set to next mm direct when mm has MMF_DISABLE_THP_COMPLETELY Message-ID: References: <20251215090419.174418-1-yanglincheng@kylinos.cn> <20251215090419.174418-5-yanglincheng@kylinos.cn> <11025f1c-88d3-41a9-8290-21a9565e9bc3@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11025f1c-88d3-41a9-8290-21a9565e9bc3@kernel.org> X-Rspam-User: X-Rspamd-Queue-Id: 33E701A000C X-Rspamd-Server: rspam10 X-Stat-Signature: k9qe5u61ron15h1inic4byjyz9g5wkao X-HE-Tag: 1766122309-579741 X-HE-Meta: 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 pMSBg4oq 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 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: List-Subscribe: List-Unsubscribe: On Thu, Dec 18, 2025 at 10:33:16AM +0100, David Hildenbrand (Red Hat) wrote: > On 12/15/25 10:04, Vernon Yang wrote: > > When an mm with the MMF_DISABLE_THP_COMPLETELY flag is detected during > > scanning, directly set khugepaged_scan.mm_slot to the next mm_slot, > > reduce redundant operation. > > That conceptually makes sense to me. How much does that safe in practice? Do > you have some performance numbers for processes with rather large number of > VMAs? I also only came to this possibility through theoretical analysis and haven't did any separate performance tests for this patch now. If you have anything you'd like to test, please let me know, and I can test the performance benefits. > -- > Cheers > > David -- Thanks, Vernon