Function sysctl_swap_fragmentation

freebsd/vm/swap_pager.c:907–932

* SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats */

 * SYSCTL_SWAP_FRAGMENTATION() -	produce raw swap space stats
 */
static int
sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS)
{
	struct sbuf sbuf;
	struct swdevt *sp;
	const char *devname;
	int error;

	error = sysctl_wire_old_buffer(req, 0);
	if (error != 0)
		return (error);
	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
	mtx_lock(&sw_dev_mtx);
	TAILQ_FOREACH(sp, &swtailq, sw_list) {
		if (vn_isdisk(sp->sw_vp))
			devname = devtoname(sp->sw_vp->v_rdev);
		else
			devname = "[file]";
		sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname);
		blist_stats(sp->sw_blist, &sbuf);
	}
	mtx_unlock(&sw_dev_mtx);
	error = sbuf_finish(&sbuf);
	sbuf_delete(&sbuf);
	return (error);
}

/*
 * SWAP_PAGER_FREESPACE() -	frees swap blocks associated with a page