From owner-svn-src-head@freebsd.org Sun Jan 22 19:46:16 2017 Return-Path: Delivered-To: svn-src-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 4095ECBC43D; Sun, 22 Jan 2017 19:46:16 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::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 EA827A08; Sun, 22 Jan 2017 19:46:15 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id v0MJkF8B092987; Sun, 22 Jan 2017 19:46:15 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id v0MJkFHH092986; Sun, 22 Jan 2017 19:46:15 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201701221946.v0MJkFHH092986@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Sun, 22 Jan 2017 19:46:15 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r312648 - head/share/man/man5 X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Jan 2017 19:46:16 -0000 Author: kib Date: Sun Jan 22 19:46:14 2017 New Revision: 312648 URL: https://svnweb.freebsd.org/changeset/base/312648 Log: Editing and clarifications for tmpfs(5). Submitted by: wblock Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D9211 Modified: head/share/man/man5/tmpfs.5 Modified: head/share/man/man5/tmpfs.5 ============================================================================== --- head/share/man/man5/tmpfs.5 Sun Jan 22 19:41:42 2017 (r312647) +++ head/share/man/man5/tmpfs.5 Sun Jan 22 19:46:14 2017 (r312648) @@ -77,7 +77,7 @@ tmpfs_load="YES" .Sh DESCRIPTION The .Nm -driver implements in-memory, or +driver implements an in-memory, or .Tn tmpfs file system. The filesystem stores both file metadata and data in main memory. @@ -85,22 +85,22 @@ This allows very fast and low latency ac The data is volatile. An umount or system reboot invalidates it. These properties make the filesystem's mounts suitable for fast -scratch storage, e.g. +scratch storage, like .Pa /tmp . .Pp If the system becomes low on memory and swap is configured (see .Xr swapon 8 ), -file data may be written to the swap space, freeing memory +the system can transfer file data to swap space, freeing memory for other needs. -The current implementation never swaps out metadata, including -the directory content. +Metadata, including the directory content, is never swapped out by the +current implementation. Keep this in mind when planning the mount limits, especially when expecting to place many small files on a tmpfs mount. .Pp -When a file from a tmpfs mount is mmaped (see -.Xr mmap 2 ) -into the process address space, the swap VM object which manages the file -pages is used to implement mapping and to avoid double-copying of +When +.Xr mmap 2 +is used on a file from a tmpfs mount, the swap VM object managing the +file pages is used to implement mapping and avoid double-copying of the file data. This quirk causes process inspection tools, like .Xr procstat 1 ,