top - 08:47:46 up 37 min, 4 users, load average: 1.91, 1.75, 1.70 Tasks: 360 total, 1 running, 359 sleeping, 0 stopped, 0 zombie %Cpu(s): 3.0 us, 1.4 sy, 0.0 ni, 90.0 id, 5.6 wa, 0.0 hi, 0.1 si, 0.0 st KiB Mem : 5700592 total, 1711476 free, 1723544 used, 2265572 buff/cache KiB Swap: 8257532 total, 8257532 free, 0 used. 3075436 avail Mem
[root@ractw21 ~]# sync; echo 3 > /proc/sys/vm/drop_caches
top - 08:49:49 up 39 min, 5 users, load average: 1.72, 1.74, 1.70 Tasks: 360 total, 2 running, 358 sleeping, 0 stopped, 0 zombie %Cpu(s): 4.7 us, 1.6 sy, 0.0 ni, 91.8 id, 1.9 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 5700592 total, 2731316 free, 1715292 used, 1253984 buff/cache KiB Swap: 8257532 total, 8257532 free, 0 used. 3088148 avail Mem
The command
# sync; echo 3 > /proc/sys/vm/drop_caches
has freed up about 1 Gbyte Memmory very quickly
2265572 buff/cache -> 1253984 buff/cache
1711476 free -> 2731316 free
Note over time the buffer cache will very likely regain its pages !
Reference