Lines Matching +full:on +full:- +full:the +full:- +full:fly
1 .. SPDX-License-Identifier: GPL-2.0
10 Everything in tmpfs is temporary in the sense that no files will be
11 created on your hard drive. If you unmount a tmpfs instance,
14 tmpfs puts everything into the kernel internal caches and grows and
15 shrinks to accommodate the files it contains and is able to swap
17 be adjusted on the fly via 'mount -o remount ...'
19 If you compare it to ramfs (which was the template to create tmpfs)
20 you gain swapping and limit checking. Another similar thing is the RAM
22 RAM, where you have to create an ordinary filesystem on top. Ramdisks
23 cannot swap and you do not have the possibility to resize them.
25 Since tmpfs lives completely in the page cache and on swap, all tmpfs
28 (shmem, see ipcs(1)). The most reliable way to get the count is
31 tmpfs has the following uses:
37 This mount does not depend on CONFIG_TMPFS. If CONFIG_TMPFS is not
38 set, the user visible part of tmpfs is not built. But the internal
42 POSIX shared memory (shm_open, shm_unlink). Adding the following
47 Remember to create the directory that you intend to mount tmpfs on
50 This mount is _not_ needed for SYSV shared memory. The internal
51 mount is used for that. (In the 2.3 kernel versions it was
52 necessary to mount the predecessor of tmpfs (shm fs) to use SYSV
56 e.g. on /tmp and /var/tmp and have a big swap partition. And now
60 4) And probably a lot more I do not know about :-)
66 size The limit of allocated bytes for this tmpfs instance. The
68 oversize your tmpfs instances the machine will deadlock
69 since the OOM handler will not be able to free that memory.
70 nr_blocks The same as size, but in blocks of PAGE_SIZE.
71 nr_inodes The maximum number of inodes for this instance. The default
72 is half of the number of your physical RAM pages, or (on a
73 machine with highmem) the number of lowmem RAM pages,
74 whichever is the lower.
78 can be changed on remount. The size parameter also accepts a suffix %
80 the default, when neither size nor nr_blocks is specified, is size=50%
85 use up all the memory on the machine; but enhances the scalability of
89 tmpfs has a mount option to set the NUMA memory allocation policy for
90 all files in that instance (if CONFIG_NUMA is enabled) - which can be
91 adjusted on the fly via 'mount -o remount ...'
94 mpol=default use the process allocation policy
96 mpol=prefer:Node prefers to allocate memory from the given Node
100 mpol=local prefers to allocate memory from the local node
103 NodeList format is a comma-separated list of decimal numbers and ranges,
104 a range being two hyphen-separated decimal numbers, the smallest and
105 largest node numbers in the range. For example, mpol=bind:0-3,5,7,9-15
108 use at file creation time. When a task allocates a file in the file
109 system, the mount option memory policy will be applied with a NodeList,
110 if any, modified by the calling task's cpuset constraints
111 [See Documentation/admin-guide/cgroup-v1/cpusets.rst] and any optional flags,
112 listed below. If the resulting NodeLists is the empty set, the effective
113 memory policy for the file will revert to "default" policy.
117 when tmpfs is mounted by appending them to the mode before the NodeList.
118 See Documentation/admin-guide/mm/numa_memory_policy.rst for a list of
119 all available memory allocation policy mode flags and their effect on
127 For example, mpol=bind=static:NodeList, is the equivalent of an
130 Note that trying to mount a tmpfs with an mpol option will fail if the
132 specifies a node which is not online. If your system relies on that
135 online, then it is advisable to omit the mpol option from automatic
136 mount options. It can be added later, when the tmpfs is already mounted
137 on MountPoint, by 'mount -o remount,mpol=Policy:NodeList MountPoint'.
140 To specify the initial root directory you can use the following mount
144 mode The permissions as an octal number
145 uid The user id
146 gid The group id
149 These options do not have any effect on remount. You can change these
150 parameters with chmod(1), chown(1) and chgrp(1) on a mounted filesystem.
153 tmpfs has a mount option to select whether it will wrap at 32- or 64-bit inode
157 inode64 Use 64-bit inode numbers
158 inode32 Use 32-bit inode numbers
161 On a 32-bit kernel, inode32 is implicit, and inode64 is refused at mount time.
162 On a 64-bit kernel, CONFIG_TMPFS_INODE64 sets the default. inode64 avoids the
163 possibility of multiple files with the same inode number on a single device;
164 but risks glibc failing with EOVERFLOW once 33-bit inode numbers are reached -
165 if a long-lived tmpfs is accessed by 32-bit applications so ancient that
169 So 'mount -t tmpfs -o size=10G,nr_inodes=10k,mode=700 tmpfs /mytmpfs'
170 will give you tmpfs instance on /mytmpfs which can allocate 10GB