What exactly is "Memory Used" in ganglia (versus "Memory Cached")? Does "Memory Used" refer to physical memory, virtual memory, resident memory, or shared memory?
Does it include memory used by code, data, and shared memory among tasks?
What about "Memory Cached"? Thank you.
According to Red Hat, the cached memory is memory used for the "Page Cache" in Linux. This is the result of Linux using RAM to cache the contents of frequently-used disk data in order to speed up I/O operations. This thread from the Ganglia general mailing list seems to back that up. This assumes you have Ganglia running on Linux.
In my experience, on the Ganglia graph, "Memory Used" is the chunk of physical memory used, out of the "Total In-Core Memory" available.
