Date: Mon, 9 Jul 2018 08:51:30 +1000 From: Peter Jeremy <peter@rulingia.com> To: Warner Losh <imp@bsdimp.com> Cc: "Rodney W. Grimes" <rgrimes@freebsd.org>, Hans Petter Selasky <hselasky@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r336025 - in head/sys: amd64/include i386/include Message-ID: <20180708225130.GD78412@server.rulingia.com> In-Reply-To: <CANCZdfpZpeCVSs1%2BMptwuN76SED-W4XyLCyQfrd4OpGwFk8Hrg@mail.gmail.com> References: <201807061013.w66ADgbJ087546@repo.freebsd.org> <201807061532.w66FWPEN052842@pdx.rh.CN85.dnsmgr.net> <CANCZdfpZpeCVSs1%2BMptwuN76SED-W4XyLCyQfrd4OpGwFk8Hrg@mail.gmail.com>
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--u3/rZRmxL6MmkK24 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2018-Jul-06 09:47:00 -0600, Warner Losh <imp@bsdimp.com> wrote: >On UP systems, these additional opcodes are harmless. They take a few extra >cycles (since they lock an uncontested bus) and add a couple extra memory >barriers (which will be NOPs). On MP systems, atomics now work by default. Atomics in modules used to work by default (at least on x86) - they were explicitly not inlined so that modules on UP systems didn't have to include the lock and barrier instructions that were very expensive on some systems 20 years ago. That said, those systems are (hopefully) all dead now so moving to inlining SMP versions of atomic operations in modules is probably the correct decision now. --=20 Peter Jeremy --u3/rZRmxL6MmkK24 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE7rKYbDBnHnTmXCJ+FqWXoOSiCzQFAltClXJfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEVF QjI5ODZDMzA2NzFFNzRFNjVDMjI3RTE2QTU5N0EwRTRBMjBCMzQACgkQFqWXoOSi CzT7Kw/+PR9PTELv+1R/P4k+ZG9IRaG1CDcnodf+kvs/REVYV6VOYlKyuKepaBe4 OqwFd7h/7ws2myrjInl+REtHgKA5Le7voXK2ox0A8sGBxNTcebkQZwpEJhNqDy0O kUrKiJ3WoThoq0C3Wd2FgrXBvCLzn/qcwIFsQ679vOs7kl5bVUSUC8/3N9IpI/Gz Bks0wD3a6gV9YCil5MnsMUQMxwi39cKq47u4FWXSPEHpGx0MWkxXT7lLPFpaB4mB R67tkKC1V7qMzKWZu0POzQrWe0/z8CrempK7SKjPkHTeObMvTgjuZp5KWme591rE 1Wve9pbMpk995AoyjH2xoaucIdXxtm6vpmaEBYMKv4hEGj20i5lqrKW5F2eX4Nsu 0LOKN5Ri8xAkhOqF4VxZurtWpeTJDUjs2skPfdQq/gwWNSG2usVri3cvYigUpnYk ITSWrwXPRptw+9RtW/zsr+x2QoA3QvCbShsUjxE3RhlrmiPwDEex4mFNAizD2WBp ljvnYuEiTHWg3kMQwo+Z/fYU/dNZ1ff5VuT5O05wu/sq60NyuYRZgaTHghfaKZ0g QCWeBTaQ2PMvdIjV1Ym1ipJ5Osq7o17SXToLLZwJxE2Geycw6Ns8cYNkKvud1ew2 QRdxiBGXqjpTxzT41Nxcqb7zWZFARMpMlZsHyRa7aXS/KFVHdtE= =9XaV -----END PGP SIGNATURE----- --u3/rZRmxL6MmkK24--
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