StatsDawg

This graphs shows the percentage of RAM and swap in use. It is important to note that the amount of RAM does not include buffers and cache. These are managed by Linux in an effort to make the system run as efficiently as possible. As a result, Linux will generally use up to 90% or more of RAM, when most of this is actually buffered or cached data. Often times, the RAM used for buffers and cache can be reallocated when a process requsts additional memory. Therefore, the memory graph takes this into account, showing you only memory that has been allocated for processes and their data.

Note that high RAM usages does not usually indicate a problem in situations where your swap usage is less than 10%. Elevated swap usage, tailored with high I/O wait percentages indicated by the CPU Graph mean that your system is relying on your swap space, which can have a drastic effect on performance. If this happens frequently, a RAM upgrade would be advisable.