From owner-svn-src-all@FreeBSD.ORG Mon Jan 26 02:15:22 2009 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A8FD7106564A; Mon, 26 Jan 2009 02:15:22 +0000 (UTC) (envelope-from trhodes@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 96EF28FC14; Mon, 26 Jan 2009 02:15:22 +0000 (UTC) (envelope-from trhodes@FreeBSD.org) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id n0Q2FMFh033463; Mon, 26 Jan 2009 02:15:22 GMT (envelope-from trhodes@svn.freebsd.org) Received: (from trhodes@localhost) by svn.freebsd.org (8.14.3/8.14.3/Submit) id n0Q2FMr9033462; Mon, 26 Jan 2009 02:15:22 GMT (envelope-from trhodes@svn.freebsd.org) Message-Id: <200901260215.n0Q2FMr9033462@svn.freebsd.org> From: Tom Rhodes Date: Mon, 26 Jan 2009 02:15:22 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r187703 - head/share/man/man7 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Jan 2009 02:15:23 -0000 Author: trhodes Date: Mon Jan 26 02:15:22 2009 New Revision: 187703 URL: http://svn.freebsd.org/changeset/base/187703 Log: Better description of kern.ipc.maxpipekva. Discussed with: kib Modified: head/share/man/man7/tuning.7 Modified: head/share/man/man7/tuning.7 ============================================================================== --- head/share/man/man7/tuning.7 Mon Jan 26 01:08:24 2009 (r187702) +++ head/share/man/man7/tuning.7 Mon Jan 26 02:15:22 2009 (r187703) @@ -403,13 +403,16 @@ on the system. .Pp The .Va kern.ipc.maxpipekva -loader tunable is used to set a hard limit on the amount of pageable -address space available. -This value is auto tuned by the system, but may require manual tuning -in a few rare cases. +loader tunable is used to set a hard limit on the +amount of kernel address space allocated to mapping of pipe buffers. +Use of the mapping allows the kernel to eliminate a copy of the +data from writer address space into the kernel, directly copying +the content of mapped buffer to the reader. Increasing this value to a higher setting, such as `25165824' might -improve performance on systems where pageable address space is -quickly exhausted. +improve performance on systems where space for mapping pipe buffers +is quickly exhausted. +This exhaustion is not fatal; however, and it will only cause pipes to +to fall back to use double-copy. .Pp The .Va kern.ipc.shm_use_phys