PFFRAG_FRENT_HIWAT
pf->limit[PF_LIMIT_FRAGS] = PFFRAG_FRENT_HIWAT;
{ &pf_frent_pl, PFFRAG_FRENT_HIWAT },
pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0);