Named 问题请教

我用vmstat 看，发现free内存一直下降，不知到那去了，而且还不能释放

bash-2.05b# vmstat -w 1
procs memory       page                   disks    faults    cpu
r b w avm fre flt  re  pi  po  fr  sr wd0 wd1 in sy cs us sy id
0 5 0  21368 407120 202 0 0 0 0 0  14 6  725 774  252  1  2 97
0 5 0  21432 406912 64 0 0 0 0 0 0  11  906 673  326  0  3 97
0 5 0  21288 406768 42 0 0 0 0 0 0 7  827 670  294  0  2 98
0 5 0  21452 406604 47 0 0 0 0 0 0 7  849 669  306  1  1 98
0 5 0  21436 406380 62 0 0 0 0 0 0 8  930 670  325  0  5 95
0 5 0  21404 406220 46 0 0 0 0 0 2  10  879 668  311  0  3 97
0 5 0  21420 406060 46 0 0 0 0 0 0 9  829 656  295  0  2 98
0 5 0  21404 405932 38 0 0 0 0 0 6 4  749 520  247  0  0 100
0 5 0  21468 405772 46 0 0 0 0 0 1 6  783 552  268  0  1 99
0 5 0  21360 405640 39 0 0 0 0 0 1  11  794 594  278  0  2 98
0 5 0  21424 405480 46 0 0 0 0 0 0 6  803 621  281  0  1 99
0 5 0  21408 405304 50 0 0 0 0 0 3 7  885 636  315  1  2 97
0 5 0  21408 405160 42 0 0 0 0 0 0 8  792 613  272  0  3 97
0 5 0  21416 405008 44 0 0 0 0 0 4  14  822 593  283  0  0 100
0 5 0  21436 404844 47 0 0 0 0 0 0 8  844 625  298  1  2 98
0 5 0  21392 404648 55 0 0 0 0 0 0 5  852 624  300  0  0 100
0 5 0  21476 404420 63 0 0 0 0 0 0  10  919 656  324  0  1 99
0 5 0  21452 404156 72 0 0 0 0 0 0 8  983 607  339  0  3 97
0 5 0  21440 404024 39 0 0 0 0 0 0 6  734 568  246  0  0 100
0 5 0  21464 403808 60 0 0 0 0 0 0  10  919 611  324  0  2 98
0 5 0  21396 403636 49 0 0 0 0 0 0 6  760 549  248  0  4 96
0 5 0  21404 403388 68 0 0 0 0 0 0  10  947 604  330  0  2 98
0 5 0  21400 403152 65 0 0 0 0 0 2 6  861 582  286  0  1 99
0 5 0  21520 402840 84 0 0 0 0 0 0  11 1013 621  355  0  2 98
0 5 0  21408 402664 50 0 0 0 0 0 0 5  760 601  262  0  2 98
0 5 0  21452 402476 53 0 0 0 0 0 0 8  787 568  260  0  3 97
0 5 0  21392 402152 87 0 0 0 0 0 0  11 1047 607  355  0  4 96
0 5 0  21444 401956 55 0 0 0 0 0 0 6  761 526  249  0  1 99
0 5 0  21444 401712 74 0 0 0 0 0 3 9  961 946  322  0  4 96
0 5 0  21404 401600 36 0 0 0 0 0 1 4  679 555  225  0  2 98