[memory] Problem to flush unused memory

[ade05fr]

Hello

i have a problem to understand the memory used by my gentoo apps.
I explain : With 2.5 Gb RAM i believe that my programs never flush memory after it stopped.

What is weird is that with top command it shows me for exemple

Tasks: 137 total, 1 running, 136 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.3%us, 0.2%sy, 0.0%ni, 98.4%id, 1.0%wa, 0.0%hi, 0.2%si, 0.0%st
Mem: 2571692k total, 2154380k used, 417312k free, 35312k buffers
Swap: 1076316k total, 8k used, 1076308k free, 1805428k cached

but with gnome-monitor-system it indicates nearl 500 Mb used / 2.Gb

And it seems that top command is the "good" value.

Is it normal that these 2 commands indicates 2 differents values ?
How can i check if the memory is flush or not ?
How can i solve it ?

[Updated]
I saw that if i do "echo 1 > /proc/sys/vm/drop_cache"
my RAM memory is flushed
"Tasks: 156 total, 1 running, 155 sleeping, 0 stopped, 0 zombie
Cpu(s): 2.2%us, 0.3%sy, 0.0%ni, 97.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 2571692k total, 592960k used, 1978732k free, 996k buffers
Swap: 1076316k total, 8k used, 1076308k free, 98728k cached
"

but is it normal to do this manually ?

Thanks
Ade05fr
_________________
[LAPTOP]
DELL Inspiron 5110
i5-2450M CPU @ 2.50GHz
[LINUX-GENTOO]
Gentoo 2018-0
kernel 5.0.6
gnome 3.30

[roarinelk]

Memory is there to be used. If no application needs it, the kernel takes it to
cache disk access and other things.