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AJvYcCXcZ01/gJ0/yBnmssfvU72cpXf+JDouJHinr0vojx3FVP2qjMo1CRqUpjkgNXJLViD2PkkAe2foSA==@kvack.org X-Gm-Message-State: AOJu0YyMoB90uR5W1EgEQrp0qtnUBACysF0AGJAKPbi63ZVi9WmSvWI8 hfNolFEb8KlyV/yFg4gF1dK3oE6LHYe5c7U+sn9d6bQ+MeJ3b9pNAv5DJxGRJ+jQRvWunGlt9Wr etK7tWBsKDgChr0olSbFbwSnIVfPvSvw= X-Gm-Gg: ATEYQzwbzJIwz7Cm5Xa2RkvSjjD7m7r+cQvjmPBQP6MuUO3zD57xvV+fDJ9cfbLGrdD Jxnn5OYWzUVqkTUVfNRAxJwToSnA/vGISmoJM2/Ol0PXKG9vGIs4krESyRuYD0d/LLV8PBCYfuO MQTyiUcTxYFG6nuf5Shlzx/v7dPrl8ZemrOpeNdQ3w6Yvtjqv0zXjjSpm5m0Qu2t7gEslltuiid aQcpfRYORMW46QWq6UPMldavFGmRZhpfuZAqIgUyfp4Z8ZnsJazrOTb03JkUVelW8zbLtSoMV93 1IoLvTY= X-Received: by 2002:a05:6512:234e:b0:5a0:efe2:e8f7 with SMTP id 2adb3069b0e04-5a105d85002mr1714014e87.5.1772126138043; Thu, 26 Feb 2026 09:15:38 -0800 (PST) MIME-Version: 1.0 References: <20260221093918.1456187-1-vernon2gm@gmail.com> <20260221093918.1456187-3-vernon2gm@gmail.com> <20260224035247.r6mxsfcpiev4wnce@master> <1da56bbb-9211-42d7-9b08-3ee56d2b538d@kernel.org> <8a5277e0-d70e-4849-9763-ed90e350a118@kernel.org> In-Reply-To: <8a5277e0-d70e-4849-9763-ed90e350a118@kernel.org> From: Vernon Yang Date: Fri, 27 Feb 2026 01:15:24 +0800 X-Gm-Features: AaiRm52legzJffa10RBFBIh85WSfEvEU71Jrj2lWEGgvnh79Lw3Jee2w-b-MZT4 Message-ID: Subject: Re: [PATCH mm-new v8 2/4] mm: khugepaged: refine scan progress number To: "David Hildenbrand (Arm)" Cc: akpm@linux-foundation.org, Wei Yang , lorenzo.stoakes@oracle.com, ziy@nvidia.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 4A08940007 X-Stat-Signature: dwgsp5ix5bbbhukj7cz3wao7gbjr7smj X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1772126140-506386 X-HE-Meta: U2FsdGVkX18jS7yR/Eeyrvxs/nRz71bdqKR52+HxkZYdv4ZUB/4k0EfslJsLqsy/I/mb6ekmWbkdoK9L6fPVnwwWpfyFzSRJUASVbsFyf6cZBz87nucPhZENzStIiPsCGlHsZSXYpOTezGN6jnSHMEEs4waPUx8CoqQW5ehzvOda2IH2YnBtd2wd2wo7cf6YUsO6shk9Hf5QfcaZqkDz0R4eriWDKDbsbVgq5t6g0cZy8YU/ywHNm3qoZ/XVPU/g8Yr4tl1VN7nEOn2eB/jho5MvzPZ2xuutJVW3nSsSASPlrOw28o4oqkIMA/KLBgVAzJtfSUOB2eLMrXJTHTllBJKuHNhNqLspyjV4CVJQxChfEVD9s91FIu0RRpH90qyCIxRK+jpTCuXOn8s57RpzDVNh02ASx1waaFQjJxzHa2MRLAL0fltj4FPHGn4cPNRXREqznux8l93Up3+GsIR8eccZyTuZTL68pzg34s9Z2sIiNG5DjbCsoXB4gC+pmvS7LRVuvgvHS49wlQSk+279CcSji/tZLzp37NR++U5WuhlPVLGwmzVs2CF6ptJMGgJ2LwGwahDXYvmTfLGca6YZ7zQcYYL1kN9UFabYuIA5qoKiRlrxx47rz/58VfXGddabVW2iyihwflxcwIS90hd74LNYThKNFqXgnI+HkgqrlH9rbo34MhkDhTc77cot4P/FZKPe7wz4ESEy0ipxXuuzx1SuP8yABMTTEEWtGH91tC3KYBAeD8u/OodXgutuKLbOpYh8CvXRCEveddkeT8gsswkLaiMyZNpE5r6f7U0EbcrItBpbNQZYv/+dNmomDiXEWFdBRbvg9BehMiG+vtO5BefVMBT1GmYPgTfhXRiLcEDnHzxkRN2E9mllmlCE/0btwsKBJtPCr/dYHxpggFq3Ttn0eRjR2U/1rSA+3rPoqysvMcFU5bfNn7nylqpM8ena8aMXK4VxazxIIpo+5ob fKcEljJL bsdkWrxsJvatmVYK+F0Rc//laHcvL5WACU/KqL9vdLF1exb7YYLDPSX0/kU8wmX8Bzh5DQPoGgflTRd0YI9cSqwr7v2un+A86W44VTnY+heDUgWYBFkt3OWsfBvjNh8eJoLdTXtmZTdnsUHFGpPDgBNGKdVOdMZ23j01aYqh+sbSLd7afzkOVHezb4cYVteELyFi8DqVAaclgsIxkE1kLF6x1PzFu8mCXi5BJxrZu3cc7JUFiMwwJ1QgEO9PWzK7cRo+Bm2XoZ1fpRpc3VmHbkhMLWufkyiu9Dy/KjQk5GsILcMbKYKOwpgulMx0JBodzlAsZ+uI1VkJ90wjM0YgNB0h8ytjIKCrRwpE1hblwqVA6Tie8TClB/uNmmCE4plZNZOdTeSZbpg2bjipdFH18xWVovOWUjcGlznGHOuymjynwlgn+NMDJOFUPxRbiKiiRSJqvmqluwxHJ+P00iV9LVJj9lr8cgnvKYVd0YWebSszHbLg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Feb 26, 2026 at 11:45=E2=80=AFPM David Hildenbrand (Arm) wrote: > > On 2/26/26 15:31, Vernon Yang wrote: > > On Wed, Feb 25, 2026 at 03:29:05PM +0100, David Hildenbrand (Arm) wrote= : > >> On 2/25/26 15:25, Vernon Yang wrote: > >>> > >>> Thank you for suggestion. > >>> > >>> Placing it inside "struct collapse_control" makes the overall code > >>> simpler, there also coincidentally has a 4-bytes hole, as shown below= : > >>> > >>> struct collapse_control { > >>> bool is_khugepaged; /* 0 = 1 */ > >>> > >>> /* XXX 3 bytes hole, try to pack */ > >>> > >>> u32 node_load[64]; /* 4 2= 56 */ > >>> > >>> /* XXX 4 bytes hole, try to pack */ > >>> > >>> /* --- cacheline 4 boundary (256 bytes) was 8 bytes ago --- *= / > >>> nodemask_t alloc_nmask; /* 264 = 8 */ > >>> > >>> /* size: 272, cachelines: 5, members: 3 */ > >>> /* sum members: 265, holes: 2, sum holes: 7 */ > >>> /* last cacheline: 16 bytes */ > >>> }; > >>> > >>> But regardless of khugepaged or madvise(MADV_COLLAPSE), "cur_progress= " > >>> will be counted, while madvise(MADV_COLLAPSE) actually does not need = to > >>> be counted. > >>> > >>> David, do we want to place "cur_progress" inside the "struct collapse= _control"? > >> > >> Might end up looking nicer code-wise. But the reset semantics (within = a > >> pmd) are a bit weird. > >> > >>> If Yes, it would be better to rename "cur_progress" to "pmd_progress"= , > >>> as show below: > >>> > >> > >> "pmd_progress" is misleading. "progress_in_pmd" might be clearer. > >> > >> Play with it to see if it looks better :) > > > > Hi Andrew, David, > > > > Based on previous discussions [1], v2 as follow, and testing shows the > > same performance benefits. Just make code cleaner, no function changes. > > > > If David has no further revisions, Andrew, could you please squash the > > following clean into this patch? If you prefer a new version, please le= t > > me know. Thanks. > > Do we also have to update the resulting patch description? Patch itself > LGTM. No need to update the patch description. -- Cheers, Vernon