func sysHugePageOS(v unsafe.Pointer, n uintptr) {
	if physHugePageSize != 0 {
		// Round v up to a huge page boundary.
		beg := alignUp(uintptr(v), physHugePageSize)
		// Round v+n down to a huge page boundary.
		end := alignDown(uintptr(v)+n, physHugePageSize)

		if beg < end {
			madvise(unsafe.Pointer(beg), end-beg, _MADV_HUGEPAGE)
		}
	}
}

func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {