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.TH "MEMKIND_PMEM" 3 "2015-04-21" "Intel Corporation" "MEMKIND_PMEM" \" -*- nroff -*-

.SH "NAME"

memkind_pmem \- file-backed memory memkind operations.

.br

.BR Note:

This is EXPERIMENTAL API. The functionality and the header file itself can be changed (including non-backward compatible changes) or removed.

.SH "SYNOPSIS"

.sp

.BI "int memkind_pmem_create(struct memkind " "*kind" ", struct memkind_ops " "*ops" ", const char " "*name" );

.br

.BI "int memkind_pmem_destroy(struct memkind " "*kind" );

.br

.BI "void *memkind_pmem_mmap(struct memkind " "*kind" ", void " "*addr" ", size_t " "size" );

.br

.BI "int memkind_pmem_get_mmap_flags(struct memkind " "*kind" ", int " "*flags" );

.br

.SH DESCRIPTION

.PP

The pmem memory memkind operations enable memory kinds built on memory-mapped

files.  These support traditional

.B volatile

memory allocation in a fashion similar to

.BR libvmem (3)

library.  It uses the

.BR mmap (2)

system call to create a pool of volatile memory.  Such memory may have different

attributes, depending on the file system containing the memory-mapped files.

(See also

.IR http://pmem.io/pmdk/libvmem ).

.PP

The pmem memkinds are most useful when used with

.I Direct Access

storage (DAX), which is memory-addressable persistent storage

that supports load/store access without being paged via the system page cache.

A Persistent Memory-aware file system is typically used to provide this

type of access.

.PP

The most convenient way to create pmem memkinds is to use

.BR memkind_create_pmem ()

or

.BR memkind_create_pmem_with_config ()

(see

.BR memkind (3)).

.PP

.BR memkind_pmem_create ()

is an implementation of the memkind "create" operation for file-backed memory

kinds.  This allocates a space for some pmem-specific metadata, then calls

.BR memkind_arena_create ()

(see

.BR memkind_arena (3))

.PP

.BR memkind_pmem_destroy ()

is an implementation of the memkind "destroy" operation for file-backed memory

kinds.  This releases all of the resources

allocated by

.BR memkind_pmem_create ()

and allows the file system space to be reclaimed.

.PP

.BR memkind_pmem_mmap ()

allocates the file system space for a block of

.I size

bytes in the memory-mapped file associated with given kind.

The

.I addr

hint is ignored.  The return value is the address of mapped memory region or

.B MAP_FAILED

in the case of an error.

.PP

.BR memkind_pmem_get_mmap_flags ()

sets

.I flags

to

.BR "MAP_SHARED" .

See

.BR mmap (2)

for more information about these flags.

.TP

.B MEMKIND_PMEM_CHUNK_SIZE

The size of the PMEM chunk size.

.SH "COPYRIGHT"

Copyright (C) 2015 - 2019 Intel Corporation. All rights reserved.

.SH "SEE ALSO"

.BR memkind (3),

.BR memkind_arena (3),

.BR memkind_default (3),

.BR memkind_hbw (3),

.BR memkind_hugetlb (3),

.BR libvmem (3),

.BR jemalloc (3),

.BR mbind (2),

.BR mmap (2)