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Mon, 18 Dec 2023 06:34:55 -0800 (PST) Received: from smtpclient.apple ([77.137.74.70]) by smtp.gmail.com with ESMTPSA id v19-20020a170906489300b00a236378a43fsm587575ejq.62.2023.12.18.06.34.53 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Dec 2023 06:34:55 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.300.61.1.2\)) Subject: Re: [PATCH WIP v1 07/20] mm/rmap_id: track if one ore multiple MMs map a partially-mappable folio From: Nadav Amit In-Reply-To: <944d990f-3c98-4ade-8176-4e4b25eae0b8@redhat.com> Date: Mon, 18 Dec 2023 16:34:42 +0200 Cc: Linux Kernel Mailing List , linux-mm , Andrew Morton , Linus Torvalds , Ryan Roberts , Matthew Wilcox , Hugh Dickins , Yin Fengwei , Yang Shi , Ying Huang , Zi Yan , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , "Paul E. McKenney" Content-Transfer-Encoding: quoted-printable Message-Id: <4FFED5A1-BF86-480D-8CB7-BECE5C413B44@gmail.com> References: <20231124132626.235350-1-david@redhat.com> <20231124132626.235350-8-david@redhat.com> <944d990f-3c98-4ade-8176-4e4b25eae0b8@redhat.com> To: David Hildenbrand X-Mailer: Apple Mail (2.3774.300.61.1.2) X-Rspamd-Queue-Id: A549A14001E X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 8xqkadya9oq7ms5roeri6kxinpordfdg X-HE-Tag: 1702910097-380718 X-HE-Meta: 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 QxRhAj+r 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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 Dec 18, 2023, at 4:04=E2=80=AFPM, David Hildenbrand = wrote: >=20 > But adding 1 "0" bit is not sufficient for handling order-2 folios (P = =3D 4), only for handling order-1 folios. So what the current approach = does is the following (P =3D 4): >=20 > RMAP-ID | | Subid | > ----------------------------------- > 0 | 0000 | 0 | 0000 0000 > 1 | 0001 | 1 | 0000 0001 > 2 | 0010 | 5 | 0000 0101 > 3 | 0011 | 6 | 0000 0110 > 4 | 0100 | 25 | 0001 1001 > 5 | 0101 | 26 | 0001 1010 > 6 | 0110 | 30 | 0001 1110 > 7 | 0111 | 31 | 0001 1111 > 8 | 1000 | 125 | 0111 1101 > 9 | 1001 | 126 | 0111 1110 > 10 | 1010 | 130 | 1000 0010 > 11 | 1011 | 131 | 1000 0011 > 12 | 1100 | 150 | 1001 0110 > 13 | 1101 | 151 | 1001 0111 > 14 | 1110 | 155 | 1001 1011 > 15 | 1111 | 156 | 1001 1100 Yes, of course. Silly me. You want to take advantage of the counter not saturating for orders K where K-1 is not a power of 2. I get your point. Not sure whether it worth the complexity though=E2=80=A6=