POSIX_MADVISE(3) | Linux Programmer's Manual | POSIX_MADVISE(3) |
posix_madvise - give advice about patterns of memory usage
#include <sys/mman.h>
int posix_madvise(void *addr, size_t len, int advice);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
posix_madvise():
The posix_madvise() function allows an application to advise the system about its expected patterns of usage of memory in the address range starting at addr and continuing for len bytes. The system is free to use this advice in order to improve the performance of memory accesses (or to ignore the advice altogether), but calling posix_madvise() shall not affect the semantics of access to memory in the specified range.
The advice argument is one of the following:
On success, posix_madvise() returns 0. On failure, it returns a positive error number.
Support for posix_madvise() first appeared in glibc version 2.2.
POSIX.1-2001.
POSIX.1 permits an implementation to generate an error if len is 0. On Linux, specifying len as 0 is permitted (as a successful no-op).
In glibc, this function is implemented using madvise(2). However, since glibc 2.6, POSIX_MADV_DONTNEED is treated as a no-op, because the corresponding madvise(2) value, MADV_DONTNEED, has destructive semantics.
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2017-09-15 | Linux |