From owner-svn-doc-head@freebsd.org Sun Jul 19 19:27:27 2015 Return-Path: Delivered-To: svn-doc-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id AB5DE9A64A7; Sun, 19 Jul 2015 19:27:27 +0000 (UTC) (envelope-from wblock@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 8287B1D22; Sun, 19 Jul 2015 19:27:27 +0000 (UTC) (envelope-from wblock@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.70]) by repo.freebsd.org (8.14.9/8.14.9) with ESMTP id t6JJRRxE029794; Sun, 19 Jul 2015 19:27:27 GMT (envelope-from wblock@FreeBSD.org) Received: (from wblock@localhost) by repo.freebsd.org (8.14.9/8.14.9/Submit) id t6JJRRed029793; Sun, 19 Jul 2015 19:27:27 GMT (envelope-from wblock@FreeBSD.org) Message-Id: <201507191927.t6JJRRed029793@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: wblock set sender to wblock@FreeBSD.org using -f From: Warren Block Date: Sun, 19 Jul 2015 19:27:27 +0000 (UTC) To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r47018 - head/en_US.ISO8859-1/htdocs/news/status X-SVN-Group: doc-head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-doc-head@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for the doc tree for head List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 19 Jul 2015 19:27:27 -0000 Author: wblock Date: Sun Jul 19 19:27:26 2015 New Revision: 47018 URL: https://svnweb.freebsd.org/changeset/doc/47018 Log: Restore mysteriously lost portion of PCID report, add URL to repository commit. Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2015-04-2015-06.xml Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2015-04-2015-06.xml ============================================================================== --- head/en_US.ISO8859-1/htdocs/news/status/report-2015-04-2015-06.xml Sun Jul 19 18:50:12 2015 (r47017) +++ head/en_US.ISO8859-1/htdocs/news/status/report-2015-04-2015-06.xml Sun Jul 19 19:27:26 2015 (r47018) @@ -1085,6 +1085,11 @@ + + Commit + r282684 + +

Process-Context Identifiers (PCIDs) is a feature of the Translation Lookaside Buffer (TLB) on Intel processors, @@ -1128,7 +1133,28 @@ performed. As result, the new implementation issues exactly the same amount of shootdown IPIs as pmap which does not utilize PCID.

+ +

Another change included with the PCID rewrite is a move of + the address space switching code from assembler to C source, + making the algorithm easier to understand and validate.

+ +

Measurements done with hwpmc(4) on a Haswell machine + indicated that the new implementation reduced the amount of + data TLB misses up to 10 times, without an impact on the IPI + counters.

+ +

The rewrite was committed to HEAD at r282684.

+ +

Note: AMD processors do not have PCID feature for host paging + (AMD provides ASIDs for SVM use). But it is likely that AMD + processors do cache TLB translations for different address + spaces transparently, and snoop writes to the page tables to + invalidate the caches.

+ + + The FreeBSD Foundation +