Date: Mon, 18 Aug 2014 14:26:21 -0600 From: Warner Losh <imp@bsdimp.com> To: Peter Grehan <grehan@freebsd.org> Cc: arch@freebsd.org Subject: Re: superpages for UMA Message-ID: <257A0976-7C5E-4029-AF32-BFB3A6C60832@bsdimp.com> In-Reply-To: <53F25E60.5050109@freebsd.org> References: <53F215A9.8010708@FreeBSD.org> <20140818183925.GP2737@kib.kiev.ua> <CAJUyCcM7ZipmYu8OLxT2TCPjS%2BCSTGPRnotdKgchoNQH8s8ndA@mail.gmail.com> <53F25E60.5050109@freebsd.org>
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--Apple-Mail=_4C658C27-60E7-4EE6-BC54-329709FB8759 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 On Aug 18, 2014, at 2:13 PM, Peter Grehan <grehan@freebsd.org> wrote: >> Newer Intel CPUs have more entries, and AMD CPUs have long (since >> Barcelona) had more. In particular, they allow 2 MB page mappings to = be >> cached in a larger L2 TLB. Nowadays, the trouble is with the 1 GB = pages. >> A lot of CPUs still only support an 8 entry, 1 level TLB for 1 GB = pages. >=20 > There are new(ish) ones effectively without 1GB pages. =46rom the = "Software Optimization Guide for AMD Family 16h Processors" >=20 > "Smashing" > ... > "when the Family 16h processor encounters a 1-Gbyte page size, it will = smash translations of that 1-Gbyte region into 2-Mbyte TLB entries, each > of which translates a 2-Mbyte region of the 1-Gbyte page." =93we=92ll emulate this feature designed to make things go faster in = hardware in software by doing the very thing that makes it go slow in = hardware.=94 Fun times. Performance Smashing! Warner --Apple-Mail=_4C658C27-60E7-4EE6-BC54-329709FB8759 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJT8mFtAAoJEGwc0Sh9sBEAILYQAJvi/5avR/rBR2VivBhiWVIG 3HjtyIPbTu2XE9OiyF+h4BkREZ9Wu1dyUgKnCKqYM4DPkTGdSAcRGCdSa8GqDYva xV0QU2JH2DpjXZgmlO5JKYVzDmn/7GJVd5Ix71jg5yneg8kKl4U14ZxXcboLAY36 8t020p6vzIKNkz352kXYqLR/aCle3opbzmXTtq3lMqZHc3UMptq+XIG8m91SlQWc 24CSuJOV1W1rvi0RJ2iFR3KYE9cxvA7iUTd8RsqV5aevc22DZsjBLYRuwaA5Z2uy xFVflbrv3bA2vxw1GdtJ/W3LiD1oH+GP0jTGHMMG/jmJTlL6JbnhHR3MT0l3Ue57 dsrI24GV0aarjjHx282cyn77RTsrR0N6Kn0mw1usRWYixY/k5JNqbdQoIXB2Fqyx Mt4Axj3jm9kIjRCJNVx5XCix7md2SU402ac8zXdreD42IvyyXfc6cgWXvd8WNXXK XdEyvRbQs50ktb5eXBpm9yqsRcOl6d0C0tyP7SaDCevmTn6+405Z6QytK3L9Pc+Y yWC5hFaBLw/26JFhjF2E7ysfnfH3Nn+jIS5CgmuPzzp+qXYfmRmf5HQyJ01fr0lh b+tSS4sJV1WOC+tEt/2Joiw3llJYiSO07x4hT/GatVZtk1e4RlRER/AX0suVyF4F Ry22w2qx+U8yfO094Ef1 =h2+C -----END PGP SIGNATURE----- --Apple-Mail=_4C658C27-60E7-4EE6-BC54-329709FB8759--
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