Date: Sun, 22 Jan 2017 19:46:15 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r312648 - head/share/man/man5 Message-ID: <201701221946.v0MJkFHH092986@repo.freebsd.org>
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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 ,
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