From owner-svn-src-projects@FreeBSD.ORG Sun Mar 17 20:11:09 2013 Return-Path: Delivered-To: svn-src-projects@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id A7166C30; Sun, 17 Mar 2013 20:11:09 +0000 (UTC) (envelope-from eadler@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) by mx1.freebsd.org (Postfix) with ESMTP id 83EF4B7; Sun, 17 Mar 2013 20:11:09 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.6/8.14.6) with ESMTP id r2HKB9YF035253; Sun, 17 Mar 2013 20:11:09 GMT (envelope-from eadler@svn.freebsd.org) Received: (from eadler@localhost) by svn.freebsd.org (8.14.6/8.14.5/Submit) id r2HKB9ks035252; Sun, 17 Mar 2013 20:11:09 GMT (envelope-from eadler@svn.freebsd.org) Message-Id: <201303172011.r2HKB9ks035252@svn.freebsd.org> From: Eitan Adler Date: Sun, 17 Mar 2013 20:11:09 +0000 (UTC) To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r248442 - projects/counters/share/man/man9 X-SVN-Group: projects MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-projects@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "SVN commit messages for the src " projects" tree" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 17 Mar 2013 20:11:09 -0000 Author: eadler Date: Sun Mar 17 20:11:08 2013 New Revision: 248442 URL: http://svnweb.freebsd.org/changeset/base/248442 Log: Content and English language changes Discussed with: glebius, jilles, kib Approved by: glebius (implicit) Modified: projects/counters/share/man/man9/counter.9 Modified: projects/counters/share/man/man9/counter.9 ============================================================================== --- projects/counters/share/man/man9/counter.9 Sun Mar 17 19:27:14 2013 (r248441) +++ projects/counters/share/man/man9/counter.9 Sun Mar 17 20:11:08 2013 (r248442) @@ -99,14 +99,15 @@ Subtract value of from .Nm .Fa cnt . -The API does not guarantee any protection from underflow. +The KPI does not guarantee any protection from underflow. See .Sx IMPLEMENTATION DETAILS . .It Fn counter_u64_fetch cnt Obtain current snapshot of the data collected in .Nm .Fa cnt . -The data obtained is not guaranteed to be precise. +The data obtained is not guaranteed to reflect the real cumulative +value for any moment. .It Fn counter_u64_zero cnt Clear data collected in .Nm @@ -140,8 +141,9 @@ Any write to oid zeroes it. .Sh IMPLEMENTATION DETAILS On all architectures .Nm -is implemented using per-CPU data fields, that are specially aligned in -memory, to avoid excessive CPU cache invalidation during updates. +is implemented using per-CPU data fields that are specially aligned +in memory, to avoid inter-CPU bus traffic due to shared use +of the variables between CPUs. These are allocated using .Va UMA_ZONE_PCPU .Xr uma 9