admin-guide/mm/hugetlbpage.rst

13 256M and ppc64 supports 4K and 16M.  A TLB is a cache of virtual-to-physical
93 Once a number of huge pages have been pre-allocated to the kernel huge page
106 be specified in bytes with optional scale suffix [kKmMgG].  The default huge
113 	parameter to preallocate a number of huge pages of the specified
114 	size.  Hence, hugepagesz and hugepages are typically specified in
119 	hugepagesz can only be specified once on the command line for a
128 	specified, it can not be overwritten by a hugepagesz,hugepages
151 	only be specified once on the command line.  default_hugepagesz can
154 	sized huge pages to preallocate can also be implicitly specified as
169 indicates the current number of pre-allocated huge pages of the default size.
179 over all the set of allowed nodes specified by the NUMA memory policy of the
180 task that modifies ``nr_hugepages``. The default for the allowed nodes--when the
181 task has default memory policy--is all on-line nodes with memory.  Allowed
206 requested by applications.  Writing any non-zero value into this file
226 of the in-use huge pages to surplus huge pages.  This will occur even if
228 this condition holds--that is, until ``nr_hugepages+nr_overcommit_hugepages`` is
229 increased sufficiently, or the surplus huge pages go out of use and are freed--
232 With support for multiple huge page pools at run-time available, much of
243 	hugepages-${size}kB
280 demote_size) function as described above for the default huge page-sized case.
297     numactl --interleave <node-list> echo 20 \
302     numactl -m <node-list> echo 20 >/proc/sys/vm/nr_hugepages_mempolicy
304 This will allocate or free ``abs(20 - nr_hugepages)`` to or from the nodes
305 specified in <node-list>, depending on whether number of persistent huge pages
307 allocated nor freed on any node not included in the specified <node-list>.
310 memory policy mode--bind, preferred, local or interleave--may be used.  The
314    Documentation/admin-guide/mm/numa_memory_policy.rst],
316    specified in the mempolicy as if "interleave" had been specified.
324 #. One or more nodes may be specified with the bind or interleave policy.
325    If more than one node is specified with the preferred policy, only the
334 #. The nodes allowed mask will be derived from any non-default task mempolicy,
337    shell with non-default policy, that policy will be used.  One can specify a
338    node list of "all" with numactl --interleave or --membind [-m] to achieve
341 #. Any task mempolicy specified--e.g., using numactl--will be constrained by
343    be no way for a task with non-default policy running in a cpuset with a
347 #. Boot-time huge page allocation attempts to distribute the requested number
348    of huge pages over all on-lines nodes with memory.
357 	/sys/devices/system/node/node[0-9]*/hugepages/
366 The free\_' and surplus\_' attribute files are read-only.  They return the number
371 specified node.  When this attribute is written, the number of persistent huge
372 pages on the parent node will be adjusted to the specified value, if sufficient
388   mount -t hugetlbfs \
389 	-o uid=<value>,gid=<value>,mode=<value>,pagesize=<value>,size=<value>,\
404 is specified in bytes. If ``pagesize`` is not specified the platform's
408 for that filesystem (``/mnt/huge``). The ``size`` option can be specified
409 in bytes, or as a percentage of the specified huge page pool (``nr_hugepages``).
413 for the filesystem. ``min_size`` can be specified in the same way as ``size``,
415 At mount time, the number of huge pages specified by ``min_size`` are reserved
464 ``hugepage-shm``
465 	see tools/testing/selftests/mm/hugepage-shm.c
467 ``hugepage-mmap``
468 	see tools/testing/selftests/mm/hugepage-mmap.c