TRUNCATE_INODE_PAGES(9) Memory Management in Linux TRUNCATE_INODE_PAGES(9)NAME
truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
SYNOPSIS
void truncate_inode_pages_range(struct address_space * mapping, loff_t lstart, loff_t lend);
ARGUMENTS
mapping
mapping to truncate
lstart
offset from which to truncate
lend
offset to which to truncate
DESCRIPTION
Truncate the page cache, removing the pages that are between specified offsets (and zeroing out partial page (if lstart is not page
aligned)).
Truncate takes two passes - the first pass is nonblocking. It will not block on page locks and it will not block on writeback. The second
pass will wait. This is to prevent as much IO as possible in the affected region. The first pass will remove most pages, so the search cost
of the second pass is low.
When looking at page->index outside the page lock we need to be careful to copy it into a local to avoid races (it could change at any
time).
We pass down the cache-hot hint to the page freeing code. Even if the mapping is large, it is probably the case that the final pages are
the most recently touched, and freeing happens in ascending file offset order.
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 TRUNCATE_INODE_PAGES(9)
Check Out this Related Man Page
REMAP_FILE_PAGES(2) Linux Programmer's Manual REMAP_FILE_PAGES(2)NAME
remap_file_pages - create a nonlinear file mapping
SYNOPSIS
#define _GNU_SOURCE
#include <sys/mman.h>
int remap_file_pages(void *addr, size_t size, int prot,
ssize_t pgoff, int flags);
DESCRIPTION
The remap_file_pages() system call is used to create a nonlinear mapping, that is, a mapping in which the pages of the file are mapped into
a nonsequential order in memory. The advantage of using remap_file_pages() over using repeated calls to mmap(2) is that the former
approach does not require the kernel to create additional VMA (Virtual Memory Area) data structures.
To create a nonlinear mapping we perform the following steps:
1. Use mmap(2) to create a mapping (which is initially linear). This mapping must be created with the MAP_SHARED flag.
2. Use one or more calls to remap_file_pages() to rearrange the correspondence between the pages of the mapping and the pages of the file.
It is possible to map the same page of a file into multiple locations within the mapped region.
The pgoff and size arguments specify the region of the file that is to be relocated within the mapping: pgoff is a file offset in units of
the system page size; size is the length of the region in bytes.
The addr argument serves two purposes. First, it identifies the mapping whose pages we want to rearrange. Thus, addr must be an address
that falls within a region previously mapped by a call to mmap(2). Second, addr specifies the address at which the file pages identified
by pgoff and size will be placed.
The values specified in addr and size should be multiples of the system page size. If they are not, then the kernel rounds both values
down to the nearest multiple of the page size.
The prot argument must be specified as 0.
The flags argument has the same meaning as for mmap(2), but all flags other than MAP_NONBLOCK are ignored.
RETURN VALUE
On success, remap_file_pages() returns 0. On error, -1 is returned, and errno is set appropriately.
ERRORS
EINVAL addr does not refer to a valid mapping created with the MAP_SHARED flag.
EINVAL addr, size, prot, or pgoff is invalid.
VERSIONS
The remap_file_pages() system call appeared in Linux 2.5.46; glibc support was added in version 2.3.3.
CONFORMING TO
The remap_file_pages() system call is Linux-specific.
SEE ALSO getpagesize(2), mmap(2), mmap2(2), mprotect(2), mremap(2), msync(2), feature_test_macros(7)COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2008-04-22 REMAP_FILE_PAGES(2)