The linux memory management commands vmstat-s and free-m are good memory observation commands www.2cto.com. The system is just running-bash-3.2 $ vmstat-s 30897940 total memory 184408 used memory 78848 active memory 67432 inactive memory 30713532 free memory 6356 buffer memory 105176 swap cache 4192956 total swap 0 used swap 4192956 free swap 369 non-nice user cpu ticks 0 nice user cpu ticks 537 system cpu ticks 120270 idle cpu ticks 1523 IO-wait cpu ticks 4 IRQ cpu Ticks 50 softirq cpu ticks 0 stolen cpu ticks 112896 pages paged in 9724 pages paged out 0 pages swapped in 0 pages swapped out 160886 interrupts 71964 CPU context switches 1350373112 boot time 2821 forks [root @ localhost ~] # Free-m total used free shared buffers cachedMem: 30173 179 29994 0 6 102-/+ buffers/cache: 70 30103 Swap: 4094 0 4094 ============ www.2cto.com has been running for a long time, the memory cach has a lot of [root @ localhost ssh] # vmstat-a 2 procs ----------- memory ---------- --- swap -- ----- io ---- system -- ----- cpu ------ r B swpd free inact active si so bi bo in cs us sy id wa st 0 0 0 23590020 5347780 1614948 0 0 0 1 1 0 0 0 100 0 0 0 23590020 5347772 1615016 0 0 0 4 1006 0 0 0 306 0 100 0 0 0 0 0 23590020 5347772 0 0 0 0 1615012 0 0 0 1002 0 0 0 0 0 0 301 100 0 0 0 24 23589880 0 0 5347772 0 0 0 0 0 www.2cto.com root @ localhost ssh] # vmstat-s 30897940 total memory 7302736 used memory 1610636 active memory 5346844 inactive memory 23595204 free memory 274844 buffer memory 6102092 swap cache 4192956 total swap 0 used swap 4192956 free swap 558515 non-nice user cpu ticks 1193 nice user cpu ticks 585088 system cpu ticks 2967723549 idle cpu ticks 210472 IO-wait cpu ticks 4406 IRQ cpu ticks 301885 softirq cpu ticks 0 stolen cpu ticks 543204 pages paged in 41063536 pages paged out 0 pages swapped in 0 pages swapped out 3722943494 interrupts 393601166 CPU context switches 1346660283 boot time 8934193 forks www.2cto.com [root @ localhost ssh] # vmstatprocs ----------- memory ---------- --- swap -- ----- io ------ system -- ----- cpu ------ r B swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 23595204 274848 6102060 0 0 0 0 1 1 0 0 0 100 0 0 [root @ localhost ssh] # free-m total used free shared buffers cachedMem: 30173 7131 23042 0 268-/+ buffers/cache: 5958 904 Swap: 29269 0 4094