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b=WN/hN8opfQE4WzDY0qzDO/2LAWOwpx9SpPVN0H/kYGKO4gkdkG/rzO8Wh+zORALY5 XG/esKrshYv5C1YdL+UGQt6mDKQGpgQoQleYursPSab3D/0sUQqd9UxUty4dQti7Eh 0KbtNvzPG85Ja5LhQj3Zu3BMdUvKrE5lgCQXQ2ikgyWE8JimkIv+eo3P1gUpg3Ugvi hTqNR76cEaOzEHwDfa/TtAf8J3BIjV3FYoWs6cJGcvOIBH6Qe3WcD1Ni0SoKhPwqFY F1euq2tlUE9fH1jayXdWB3b/LOF6FZTjKjhHiinGc+ISsmd3c0fq3160o6sclvAqRM RFGdUfdntKgtg== Message-ID: Date: Tue, 12 May 2026 08:34:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/7] Accelerate page migration with batch copying and hardware offload To: "Huang, Ying" Cc: Shivank Garg , akpm@linux-foundation.org, kinseyho@google.com, weixugc@google.com, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, willy@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, apopple@nvidia.com, dave@stgolabs.net, Jonathan.Cameron@huawei.com, rkodsara@amd.com, vkoul@kernel.org, bharata@amd.com, sj@kernel.org, rientjes@google.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, dave.hansen@intel.com, hannes@cmpxchg.org, jhubbard@nvidia.com, peterx@redhat.com, riel@surriel.com, shakeel.butt@linux.dev, stalexan@redhat.com, tj@kernel.org, nifan.cxl@gmail.com, jic23@kernel.org, aneesh.kumar@kernel.org, nathan.lynch@amd.com, Frank.li@nxp.com, djbw@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260428155043.39251-2-shivankg@amd.com> <98a16642-35b7-4cf9-9ee2-8de15e877920@kernel.org> <874ikdwe21.fsf@DESKTOP-5N7EMDA> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 659DB14000D X-Stat-Signature: artfiqjyh4bu1sby9jbhwtpnfbygfgoi X-HE-Tag: 1778567668-155075 X-HE-Meta: U2FsdGVkX1+nl6lKuWzgHKgyePhnLDs3NECC7Wn43dsGPCw8zXblnmpY9vbTP3I5woANsjdAbJVvO2HSV2mhM3XsiyI2nhqy5aqhkZWPHzFp2oZA2urzD40qgYuaVSJTxCvaIP8hKbqCcAmGG1lO0Rl7tLnaa0miwtZsfk/M5wmUh0pnM4YWACRiLIUn1nPdRUz7I6ZpSRQbVlPVZsQGdaIZ1M9K7k0IQm5f/CgueM5jeTq5NdS8vhgbN2D/D5k0ARF46f/MdHMb6atOOh6ko00HjQHD44/G7zmVlm6N3FCCH0DZpz8FqGqG52C7iUfpcnEuhSt/2xjg8q7zEDcnauVEp77eRTFzq7rqt7doWSlrKPhh4ENV+x+L64RgKESMQoSuMCQDosMMj+oyTjhjBmpjU0du8i4eNKCOQXu6QsLis/wH0myiOMUb0RhnbPF75FcGEIiiQWTf4U5kg4pCrFdz4H4MbVWsYg1JCYuHhsvx7l7FvAUzs0Cypa18eTZDHzOlaDmCsQh8KQmVGmb7ndYLPQG9U1/22xzZuYOJ5RQgSMG7ikeFor+kU1tTxeEgzNTMhlozYbkPjXCPNajGYVO7U2p6tEjTqntC9xjO28NrPQa0lhYzyU1FIll3uJ8kuMNcfq3g4Q9j84hQsJd4Ks/+OpdE4+gQaiq23hy16A6SZF2OLL6HV4XWUDt3nY4fear9BkaCkVjumWUwmRXEWFHXmP0nbwJqAv6C4LZW4GGKn3xAdxO1gfmFne+RSwF0bdDpW3ffSZOiOX6w10q1dCdXUF7mDcpQo6XCzhz7Qz13bItuWbgoMiR0VhCOm3V2lhr8EAHpEUoaAKEGtT6DCLf3iSDyWwVOY0FvGxSDhfTu5hGnyyxDyU18wC/XSc4w+NSpcy6foNXJ+50hGA9u4Pbf9H1UdxIb6u9EONmun6p3NYnoY3a2Aw8VMlXp7dLLtkETDC1kI50t8XdEDf4 fiD43S52 wMMwauFS4I+XePMkc/2m6LTf9+pd7rmrlogpRDKsHma9fCJLFx+CcmLEql+cR8r81yFdyeo9l7PRJgZTC5beYssjf+/4WAjeQSrv7dlh7dM4+uUKaDwAftD10fn1qf10c4roxzCsTPMA6cwtGP7PIPcT+Wt9e5yQLwR6btWet6X9CWUPrw2j6ACrWYrjJ8PT35jINAGDVG9HUJy4sfVJNgSg7Pesg1ZZWIUUnhp+QjoXJvhLtyTuDuPrGMntJDVinRE9ve3/JDnPMjMDPM2wlD9IFCUwZUVw2H7x6WPOPFKgVaRgRotEpvMmQ+xZia2ipRUbq5Ip0QqXJiz3gtPVUBnj0Rfk9uFxwFp+J Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/12/26 04:35, Huang, Ying wrote: > "David Hildenbrand (Arm)" writes: > >> On 4/28/26 17:50, Shivank Garg wrote: >>> This is the fifth RFC of the patchset to enhance page migration by > > [snip] >> >>> >>> 3. Per-caller offload selection: Today eligibility is by migrate_reason >>> only. Some are latency-tolerant, others may be not. Is reason the >>> right granularity, or do we want a per-caller hint? >> >> Isn't it sufficient to just do it based on the #folios or sth like that? >> >> If someone migrates a handful of folios, latency is likely more important (and >> batching less beneficial). >> >> I'd assume when migrating many folios, batching could just always be done. Or >> what's the concern? > > IIUC, for callers like migrate_pages syscall, it's possible that almost all > folios of a process are passed to migrate_pages(). However, I think that > we still need to keep the folio inaccessible time reasonable. Wouldn't we still want to process them in batches, only affecting folios in a batch at one point in time, not the whole address space? -- Cheers, David