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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[-- Attachment #1 --] 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. > > There are new(ish) ones effectively without 1GB pages. From the "Software Optimization Guide for AMD Family 16h Processors" > > "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." “we’ll 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.” Fun times. Performance Smashing! Warner [-- Attachment #2 --] -----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-----home | help
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