Date: Tue, 8 Jan 2013 19:21:35 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Ian Lepore <freebsd@damnhippie.dyndns.org> Cc: svn-src-head@FreeBSD.org, Oleksandr Tymoshenko <gonzo@FreeBSD.org>, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r245147 - head/sys/arm/include Message-ID: <20130108172135.GA2561@kib.kiev.ua> In-Reply-To: <1357664471.1088.131.camel@revolution.hippie.lan> References: <201301080240.r082eKVq080302@svn.freebsd.org> <20130108030022.GC82219@kib.kiev.ua> <50EBA947.1030902@freebsd.org> <20130108155641.GG82219@kib.kiev.ua> <1357664471.1088.131.camel@revolution.hippie.lan>
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--uAKRQypu60I7Lcqm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 08, 2013 at 10:01:11AM -0700, Ian Lepore wrote: > I'm just learning the armv6/v7 stuff myself right now, but I can answer > your question for our current armv4/v5 implementation... >=20 > When there is more than one mapping of a page in v4/v5 and any one of > those mappings is writable, then the pmap.c code changes all existing > mappings to be uncacheable to maintain coherency. If the writable > mapping is removed and all that remains are read/exec mappings, the > existing mappings are made cacheable again. Yes, that's just as > inefficient and expensive as it sounds. :) Interesting, so the arm/pmap.c in fact maintain pv entries even for the unmanaged pages and kernel mappings ? But this approach, requiring pv entries for the kernel mappings, makes kernel pv entries non-reclamable on the low memory condition. In fact, I cannot find any traces of the pv reclaim in the arm/pmap.c. --uAKRQypu60I7Lcqm Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iQIcBAEBAgAGBQJQ7FWeAAoJEJDCuSvBvK1B2QIP/RjN9Fome0N2bCdPF1iPpHdo 61hXwZuKgOf24W8EVKf19vJxd9OXrLiCBN/gAqx5fXStF2u3F8wjHN2Kfjsqh030 44ar2ccg2wuQ2rK1fHU9/rBryC2J4L9XyY6GReDW92T84QOevyDm9oY8k3nNW12t AVB3sqde6jdNvpYp9wzR8k6FRDUX3nRT9rsaEBO10YxIzDJvRiJuZoAGTidkIxeg Me2geRSGYJnq82Ot8ev8kRVsqOSAGWqSf+04jRoPx0etHa42gcWBdFEAfjogiZHp xRvyf0wnLlke+3rAllJRQWBTRv9KgPwkjVFdaID5JaS6XcgvHkd3Er2arUv2qpdI rZRk2Pbgo2N36r+dFY5WtY+p8sB193WwhZy5dPpzE6NDkVSF+dkhCMrNzsdmorpS 8K/dETIkTiMe3enGuHZLophS0wlUXBEJqoRX09lHzZpxtqpFn8JvMCxNn1bKfp+W gxbEOdSz12jgXzd7idUv4tsR5z24afjVv7QZZpp9JvBccNP037Qa7tQ36a7ZpO6L tKjcAHQ6zKDRWF78QUVOwb4c/v4xRjrfRFd1+DTbyj3LdzzyBrtyhh67mNku+yhb glbVuXuLHmmK6h9Hf1gI05oBCr7rti+22Siuq5nJlVB7EhOBdEMBVnfsEeiGqfx9 PYPp+8UGHC2avldRqV7u =4a0+ -----END PGP SIGNATURE----- --uAKRQypu60I7Lcqm--
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