tmpfs /dev/shm tmpfs defaults 0 0
Remember to create the directory that you intend to mount tmpfs on
- if necessary (/dev/shm is automagically created if you use devfs).
+ if necessary.
This mount is _not_ needed for SYSV shared memory. The internal
mount is used for that. (In the 2.3 kernel versions it was
nr_blocks: The same as size, but in blocks of PAGE_CACHE_SIZE.
nr_inodes: The maximum number of inodes for this instance. The default
is half of the number of your physical RAM pages, or (on a
- a machine with highmem) the number of lowmem RAM pages,
+ machine with highmem) the number of lowmem RAM pages,
whichever is the lower.
These parameters accept a suffix k, m or g for kilo, mega and giga and
tmpfs has a mount option to set the NUMA memory allocation policy for
-all files in that instance:
-mpol=interleave prefers to allocate memory from each node in turn
-mpol=default prefers to allocate memory from the local node
-mpol=bind prefers to allocate from mpol_nodelist
-mpol=preferred prefers to allocate from first node in mpol_nodelist
+all files in that instance (if CONFIG_NUMA is enabled) - which can be
+adjusted on the fly via 'mount -o remount ...'
-The following mount option is used in conjunction with mpol=interleave,
-mpol=bind or mpol=preferred:
-mpol_nodelist: nodelist suitable for parsing with nodelist_parse.
+mpol=default prefers to allocate memory from the local node
+mpol=prefer:Node prefers to allocate memory from the given Node
+mpol=bind:NodeList allocates memory only from nodes in NodeList
+mpol=interleave prefers to allocate from each node in turn
+mpol=interleave:NodeList allocates from each node of NodeList in turn
+
+NodeList format is a comma-separated list of decimal numbers and ranges,
+a range being two hyphen-separated decimal numbers, the smallest and
+largest node numbers in the range. For example, mpol=bind:0-3,5,7,9-15
+
+Note that trying to mount a tmpfs with an mpol option will fail if the
+running kernel does not support NUMA; and will fail if its nodelist
+specifies a node which is not online. If your system relies on that
+tmpfs being mounted, but from time to time runs a kernel built without
+NUMA capability (perhaps a safe recovery kernel), or with fewer nodes
+online, then it is advisable to omit the mpol option from automatic
+mount options. It can be added later, when the tmpfs is already mounted
+on MountPoint, by 'mount -o remount,mpol=Policy:NodeList MountPoint'.
To specify the initial root directory you can use the following mount
Author:
Christoph Rohland <cr@sap.com>, 1.12.01
Updated:
- Hugh Dickins <hugh@veritas.com>, 13 March 2005
+ Hugh Dickins <hugh@veritas.com>, 4 June 2007