fadvise - phpMan

FADVISE64,FADVISE64_64(2) Linux Programmer's Guide FADVISE64,FADVISE64_64(2)

NAME
fadvise64,fadvise64_64 - Give advice about file access

SYNOPSIS
long fadvise64_64 (int fs, loff_t offset, loff_t len, int advice, int fs,
loff_t offset, loff_t len, int advice);

long sys_fadvise64 (int fs, loff_t offset, loff_t len, int advice, int fs,
loff_t offset, loff_t len, int advice);

DESCRIPTION
Allows an application to to tell the kernel how it expects to use a file handle, so
that the kernel can choose appropriate read-ahead and caching techniques for access
to the corresponding file. This is similar to the POSIX version of the madvise sys-
tem call, but for file access instead of memory access. The sys_fadvise64() func-
tion is obsolete and corresponds to a broken glibc API, sys_fadvise64_64() is the
fixed version. The following are the values for the advice parameter:

FADV_NORMAL
No special treatment.

FADV_RANDOM
Expect page references in random order.

FADV_SEQUENTIAL
Expect page references in sequential order.

FADV_WILLNEED
Expect access in the near future.

FADV_DONTNEED
Do not expect access in the near future. Subsequent access of pages in this
range will succeed, but will result either in reloading of the memory con-
tents from the underlying mapped file or zero-fill-in-demand pages for map-
pings without an underlying file.

FADV_NOREUSE
Access data only once.

RETURN VALUE
delete_module returns 0 on success; otherwise, it returns one of the errors listed
in the "Errors" section.

ERRORS
-EBADF An invalid file descriptor was specified. to modify the modules.

-EINVAL
An invalid f_mapping of file, len value smaller than 0 or advice value un-
known.