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Posts: 109 | Thanked: 84 times | Joined on Sep 2014 @ India
#12
you should not use drop cache frequently.
What happens is that when you open an app, it gets copied into the memory (RAM) from the disk (MMC).
Now when you are done with the app, and close it, it is not completely removed from the RAM, it is instead cached. So when you open it the next time, it doesn't need load it again from the disk.
This loading from disk to RAM is a very slow operation. So if you free all in the drop cache app, the cached memory, your phone will have to copy the app back to the RAM when you next open it, so there might be lags there.
So apps like phone, camera, or any other frequently used app if already there in RAM will benefit you.

Now if we see the swap, it is basically ramzswap, i.e. the 1GiB RAM in N9 is divided into RAM and swap.
So whenever your ram starts filling (how much? that is decided by swappiness), some of it is moved to the swap to make space for new apps in RAM. But it is stored in compressed form in swap. So effectively you can now store more data in RAM than you could have stored if it were not divided into swap and RAM.
So you get to keep more apps open in exchange to a little time for compressing decompressing and copying stuff. This copying is fast as swap has the same speed as of RAM. but it sure takes time.

So if you do a lot of multitasking, ramzswap will benefit you, if not, it is unnecessarily slowing things down.
You can change the swappiness or disable swap completely.

So if you have less or no apps open and still see lot of RAM used, let it be that way.
But if you have lots of apps open, your memory is almost full and probably your swap too. Then you will have to close apps to make room for new ones, or worst case restart to clear swap, as there is no other method to clear swap (not that i am aware of).
 

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