PAGE_CACHE_ASYNC_REA(9) Memory Management in Linux PAGE_CACHE_ASYNC_REA(9)NAME
page_cache_async_readahead - file readahead for marked pages
void page_cache_async_readahead(struct address_space * mapping, struct file_ra_state * ra, struct file * filp, struct page * page,
pgoff_t offset, unsigned long req_size);
address_space which holds the pagecache and I/O vectors
file_ra_state which holds the readahead state
passed on to ->readpage and ->readpages
the page at offset which has the PG_readahead flag set
start offset into mapping, in pagecache page-sized units
hint: total size of the read which the caller is performing in pagecache pages
page_cache_async_readahead should be called when a page is used which has the PG_readahead flag; this is a marker to suggest that the
application has used up enough of the readahead window that we should start pulling in more pages.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 PAGE_CACHE_ASYNC_REA(9)
Check Out this Related Man Page
READAHEAD(2) Linux Programmer's Manual READAHEAD(2)NAME
readahead - perform file readahead into page cache
#define _GNU_SOURCE /* See feature_test_macros(7) */
ssize_t readahead(int fd, off64_t offset, size_t count);
readahead() populates the page cache with data from a file so that subsequent reads from that file will not block on disk I/O. The fd
argument is a file descriptor identifying the file which is to be read. The offset argument specifies the starting point from which data
is to be read and count specifies the number of bytes to be read. I/O is performed in whole pages, so that offset is effectively rounded
down to a page boundary and bytes are read up to the next page boundary greater than or equal to (offset+count). readahead() does not read
beyond the end of the file. readahead() blocks until the specified data has been read. The current file offset of the open file referred
to by fd is left unchanged.
On success, readahead() returns 0; on failure, -1 is returned, with errno set to indicate the cause of the error.
EBADF fd is not a valid file descriptor or is not open for reading.
EINVAL fd does not refer to a file type to which readahead() can be applied.
The readahead() system call appeared in Linux 2.4.13; glibc support has been provided since version 2.3.
The readahead() system call is Linux-specific, and its use should be avoided in portable applications.
SEE ALSO lseek(2), madvise(2), mmap(2), posix_fadvise(2), read(2)COLOPHON
This page is part of release 3.44 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 2010-09-10 READAHEAD(2)
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