Using lgrp_nlgrps()

The lgrp_nlgrps(3LGRP) function returns the number of locality groups in the system. If a system has only one locality group, memory placement optimizations have no effect.

#include <sys/lgrp_user.h>
int lgrp_nlgrps(lgrp_cookie_t cookie);

The lgrp_nlgrps() function takes a cookie that represents a snapshot of the lgroup hierarchy and returns the number of lgroups available in the hierarchy.

The lgrp_nlgrps() function returns EINVAL when the cookie is invalid.