nmadvise(3)						     Library Functions Manual						       nmadvise(3)

NAME

       nmadvise - Advise the system of the expected paging behavior of a process (libnuma).

SYNOPSIS

       #include <numa.h> #include <sys/nman.h>

       int nmadvise(
	       void *addr,
	       long len,
	       int behav,
	       memalloc_attr_t *attr );

PARAMETERS

       The  parameters	to  the nmadvise() function are the same as for madvise(), with the addition of the attr parameter: Points to the starting
       address of one memory region, or a list of starting addresses and lengths for multiple regions, to which the advice refers.  If a  positive
       value, specifies the length, in bytes, of one region starting at the address specified by the addr parameter.

	      If  a  negative  value,  specifies  that	the addr parameter points to an array of regions (an array of starting addresses and their
	      lengths). In this case, -len indicates the number of regions in the array. See the description  of  the  nmemalloc_range_t  type	in
	      numa_types(4)  for  more	information about the type used for array elements.  Specifies the behavior of the region. See DESCRIPTION
	      for details.  Points to a structure containing the memory allocation policy and attributes that will be assigned to  the	region	or
	      regions specified by the addr and len parameters.

DESCRIPTION

       The  nmadvise()	function  permits a process to advise the system about its expected future behavior in referencing a mapped file or shared
       memory region. The nmadvise() function supports the following flags for the behav parameter, in addition to those documented in madvise(2):
       Prepare	the  specified	range  or object for migration to the memory regions specified by the memory allocation policy attributes. Without
       this flag, only new allocations occur from the regions specified by the new allocation policy attributes.  This flag may be logically  ORed
       with the MADV_CURRENT flag to indicate that the application should wait for migration to occur.	Without this flag, the nmadvise() function
       may return before all of the pages in the range have been migrated or replicated,  subject  to  resource  availability.	If  the  requested
       resources  are not available, the function will terminate when the resources are exhausted. See MADV_INSIST.  When used in conjunction with
       MADV_WAIT,  when the requested resource is exhausted, the remaining memory will be paged out to the backing store.

       If, in the structure pointed to by attr, the mattr_policy member is MPOL_DIRECTED and the mattr_rad member is  RAD_NONE,  the  mattr_radset
       member specifies the set of Resource Affinity Domains (RADs) where the pages of the specified range will be allocated.

       If  the	mattr_radset  member is NULL, the system will select a RAD for the memory object from among all of the RADs in the caller's parti-
       tion. In this case, the overflow set will be NULL.

       If the attr parameter is NULL, any behav flags specific to nmadvise()are ignored, and the function is equivalent to madvise().

NOTES

       As with madvise(), the behaviors specified with nmadvise() are considered by the system to be hints, and may  in  fact,	be  unimplemented.
       Unimplemented behaviors will always return success.

RETURN VALUES

       Success.  Failure. In this case, errno is set to indicate the error.

ERRORS

       If  the	nmadvise() function fails,  it sets errno is set to one of the following values for the reason specified: A non-NULL attr argument
       points to an invalid address.  The behav parameter is invalid.  The structure pointed to by the attr argument contains  an  invalid  memory
       allocation policy, an invalid RAD, or an invalid RAD set.  The behav parameter specifies MADV_SPACEAVAIL, and resources cannot be reserved.

SEE ALSO

       Functions: madvise(2), nmmap(3), numa_intro(3)

       Files: numa_types(4)

																       nmadvise(3)