![]() But the graphs have no units which does limit their usefulness. The graph calls this DATA (which seems reasonable to me).įrom your graphs and current counters, the Mac looks fairly busy from the disk point of view. The values for amount of data and current rates are on the right hand side. ![]() To the left of the graph, Activity Monitor shows that number of read and write operations (called IO in the graphs) both as totals since boot and current rates.Įach disk operation can read or write variable amounts of data. Your "memory pressure" graph is green, which indicates that macOS is able to manage memory with few bottlenecks. With a simple calculation, you can work out that your Free Memory is only 0.10 GB. So it is true that Memory Used + Cached Files is always less than or equal to Physical RAM. Memory Used + Cached Files + Free memory = Physical Memory But that is what Activity Monitor calls it. I don't like the use of "memory used" in this context because, in reality, nearly all the physical RAM is usefully occupied. Wired memory is memory which can't be compressed or swapped. Memory allocations can be counted in more than one way, but as presented by Activity Monitor:Īpp Memory + Wired memory + Compressed = Memory Used Ideally, the memory tuning will have chosen application memory that is unlikely to be wanted for some time. MacOS's memory tuning has a preference for compression rather than swapping, though in your example, it has decided that rather a lot of memory must be taken out of physical RAM and placed in the swap files. With SSDs, this is quicker and leads to a more responsive feel to the system. When boot disks were hard disks, this was a key cause of slow system response. This moving portions of memory out and in to RAM is called swapping and the disk space used is in one or more swap files.Ĭompressing and decompressing is a relatively fast action using a highly efficient algorithm. When an application requires to use that memory, it will have to be brought back into physical RAM. In your case, 6.64 GB of disk space in being used in this way. Move some portions of memory out of physical RAM and store them on the boot disk. ![]() Of course, the memory will need to be decompressed before it is next used. In your example, 906 MB of physical RAM is being used to store some unspecified (but probably about twice that) of macOS and application memory. In that case, the memory management of macOS frees up RAM in two ways: ![]() There are time when macOS and your running applications need more memory can than comfortably fit in physical RAM. In your example, the cores are only lightly loaded and not sufficient to make significant use of hyper-threading. The second physical is in graphs 3 and 4, and so on. The first physical core is shown as the first two virtual cores in the graphs. There are circumstances where this can slow throughput, but it is usually beneficial.Īctivity monitor presents all 8 virtual cores. This has the benefit of allowing the cores to more rapidly change from running one process thread to another thread (quite likely from a different process). Your CPU has 4 cores, but also has Hyper-threading which presents 8 virtual cores to the operating system. I am writing this because I feel that Elin answer is, in some parts, misleading. I have taken your questions as relating to four areas which I will attempt to answer in the same sequence.
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