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Howlett" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/2] regmap: Add maple tree based register cache Message-ID: <149d2462-a190-4480-a501-d645a84ec1bf@sirena.org.uk> References: <20230325-regcache-maple-v3-0-23e271f93dc7@kernel.org> <20230325-regcache-maple-v3-2-23e271f93dc7@kernel.org> <20230403154508.qia42tyasj4vhtm5@revolver> <6f49fdf0-c373-46f7-89bd-f30f0fb68c15@sirena.org.uk> <20230403182644.uylyonu6w6l63oze@revolver> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="uCJRLG+x40+NiNKG" Content-Disposition: inline In-Reply-To: <20230403182644.uylyonu6w6l63oze@revolver> X-Cookie: Membership dues are not refundable. X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 855A0160006 X-Stat-Signature: rg45gpsjm4dg9sq9warowic4han8rag4 X-HE-Tag: 1680547230-276322 X-HE-Meta: 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 H5NK3kPY zEplMA9/r8sXVViI0GbAa4LgQOm3Qw9NcLuvpX9vvz6ops5cKFWVoGINl0jGgoTYcWlif36JAGVX4IeRVTorpGpICSO44ymoE6Ab8+vOfj9af0VNtMXWob6hQs7LVM3Om9+Kq0B5yIRku3WxttMY1AGy7PdKNrMH31WxmbT1Gkim/i39JJHsvjWHIpsVmKRpnFwMAirVnuZ+gv3tzEJM1Ud11/NISf+Ubn+VfwTYEXxG4GLsMv32kkQoKSh4hma1da4cMWXvhUXrjYjVUHMKSdVBhYO47WmP1/hHY3ayEQWnwdnm4bwxFPWsImrqp3VnaeQFk56WXO+Ju+EokwrDreSk2nHTVfJrAwMrAv2bI+Cc7f7k= 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: --uCJRLG+x40+NiNKG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Apr 03, 2023 at 02:26:44PM -0400, Liam R. Howlett wrote: > What you have will work. If you need more optimisations later, then we > can have another look. Yeah, what's there tests out OK. In terms of optimisation the baseline requirement is that we have to be able to pull values out faster than we'd be able to read them from the device so until we're working with MMIO devices (which people do use regmap with sometimes but aren't the common case) we can typically burn a *lot* of CPU cycles and still be doing just fine. The hot spots are basic read/write of an existing cached register, then sync and initial load in of cache defaults. --uCJRLG+x40+NiNKG Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmQrHZYACgkQJNaLcl1U h9AUrgf/UA/wWHJU2ED6xMclVK69qf4qrvaY+h8h8VonghCw2gV1pNxQ4rAqQ1GB i93wOAlCJQNDsGKkFK/TlAYamC/VImoZOQdFv4TOj/BHZ8BkRfCXEekBaODALZxx dOQEdC5rqmhUAjbuB2EZBsOEKTHNwjNkmnFXHcYifgbmQ3NcuKEcUxdWa2BNyLHq MZ0KIKgBPKMbB5gQGiI3cfNQiNG2omySomm4ipU2J2uQbv4cUy0eR9HqlbiQFmrf 0Y/qVwJbkNsIWJ8jiPxeX6FAjEYNg3Ei3D20Bam7pbc+X39LpZH8XPQuGK4Khq3g yRP1AcqWix27Fh7V4o1zKZibq66QhQ== =C0mB -----END PGP SIGNATURE----- --uCJRLG+x40+NiNKG--