MacOS – activity monitor – “0 bytes” swap used always reported

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Whenever my system gets slow, I open Activity Monitor to check my RAM usage and close any apps that are consuming a lot of memory, but that I don't absolutely need to be running. RAM usage is always completely maxed out. I'm used to seeing this:

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Now I would assume that when the system gets slow, it's from all of the overhead from VM paging, but Activity Monitor always reports my "Swap Used" as "0 bytes". This can't be the case, could it? The only reason I can imagine is if Mavericks introduced some kind of intermediary solution to RAM exhaustion before falling back to using a swapfile, but I haven't heard of anything like that.

What I want to know is:

  1. Is this actually an error in Activity Monitor, or is it correct?
  2. If it's not an error, what mechanism is being used to maintain the RAM in place of the swapfile?
  3. Is this mechanism verifiably faster than using a swapfile, and is there a way to disable it and use the swapfile by default?

Best Answer

  1. Is this actually an error in Activity Monitor, or is it correct?

    • That is how it suppose to work

  2. If it's not an error, what mechanism is being used to maintain the RAM in place of the swapfile?

    • Mavericks active memory management

  3. Is this mechanism verifiable faster than using a swapfile, and is there a way to disable it and use the swapfile by default?

    • it is faster then using actual swap to HDD, it also uses something called memory compression. It always tries to use all of the memory to handle its tasks, and will rearrange the memory according to your usage. Once that is no longer possible it will use the swap.
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