centos中释放缓存的方法

释放缓存区内存的方法
a）清理pagecache（页面缓存）
# echo  > /proc/sys/vm/drop_caches     或者 # sysctl -w vm.drop_caches=

b）清理dentries（目录缓存）和inodes
# echo  > /proc/sys/vm/drop_caches     或者 # sysctl -w vm.drop_caches=

c）清理pagecache、dentries和inodes
# echo  > /proc/sys/vm/drop_caches     或者 # sysctl -w vm.drop_caches=

[root@test4_haili_dev hadoop-2.7.]# free -m
             total       used       free     shared    buffers     cached
Mem:
-/+ buffers/cache:
Swap:
[root@test4_haili_dev hadoop-2.7.]# cat /proc/sys/vm/drop_caches

[root@test4_haili_dev hadoop-2.7.]# echo  > /proc/sys/vm/drop_caches
[root@test4_haili_dev hadoop-2.7.]# free -m
             total       used       free     shared    buffers     cached
Mem:
-/+ buffers/cache:
Swap:
[root@test4_haili_dev hadoop-2.7.]# cat /proc/sys/vm/drop_caches 

[root@test4_haili_dev hadoop-2.7.]# echo  > /proc/sys/vm/drop_caches
[root@test4_haili_dev hadoop-2.7.]# cat /proc/sys/vm/drop_caches 

[root@test4_haili_dev hadoop-2.7.]# free -m
             total       used       free     shared    buffers     cached
Mem:
-/+ buffers/cache:
Swap:
[root@test4_haili_dev hadoop-2.7.]# cat /proc/sys/vm/drop_caches

[root@test4_haili_dev hadoop-2.7.]# echo  > /proc/sys/vm/drop_caches
[root@test4_haili_dev hadoop-2.7.]# free -m
             total       used       free     shared    buffers     cached
Mem:
-/+ buffers/cache:
Swap: