快速回收linux缓存

内存告急：

free -m
             total       used       free     shared    buffers     cached
Mem:         15928      15774        154          0        298       1103
-/+ buffers/cache:      14371       1556
Swap:         7983          0       7983

grep Pss /proc/[1-9]*/smaps | awk '{total+=$2}; END {print total/1024}'
3591.84
cat /proc/slabinfo |awk 'BEGIN{sum=0;}{sum=sum+$3*$4;}END{print sum/1024/1024}'
9985.24 #slab占用较多

cat /proc/meminfo

Slab:           10894564 kB
SReclaimable:   10860552 kB
SUnreclaim:        34012 kB

echo 2 > /proc/sys/vm/drop_caches

Slab:             130720 kB
SReclaimable:      96948 kB
SUnreclaim:        33772 kB

已回收：

free -m
             total       used       free     shared    buffers     cached
Mem:         15928       4279      11648          0        296        138
-/+ buffers/cache:       3844      12083
Swap:         7983          0       7983

drop_caches接受以下三种值：

To free pagecache:
echo 1 > /proc/sys/vm/drop_caches
To free reclaimable slab objects (includes dentries and inodes):
echo 2 > /proc/sys/vm/drop_caches
To free slab objects and pagecache:
echo 3 > /proc/sys/vm/drop_caches