Sluggish performance when multitasking

Discussion in 'Mac OS X Lion (10.7)' started by blahbrah, May 13, 2012.

  1. blahbrah, May 13, 2012
    Last edited: May 13, 2012

    blahbrah macrumors 6502

    Nov 9, 2006
    So my Macbook Pro early 2011 13" tends to always run into problems when I use Amadeus Pro and as a result the entire system becomes unbearable. Here's what I've been able to gather:
    The CPU usage never really gets above using 40% so I doubt there are problems there.

    I've upgraded the RAM to OWC's 8GB and it's helped, but it's still crushing the system. Right now I have 21MB free with 1.33GB wired, 4.44 GB active and 2.18GB inactive. I know Amadeus Pro, when it does run tends to take 1 GB of ram (due to the large files I have to process).

    I'm wondering what's going on and why OSX (10.7.4) hasn't already aggressively freed the inactive RAM considering there's a very noticeable hit in performance and what I should do.

  2. throAU, May 13, 2012
    Last edited: May 13, 2012

    throAU macrumors 601


    Feb 13, 2012
    Perth, Western Australia
    OS X has not freed the RAM because no application has requested it.

    Inactive memory = cache. Cache is good, better than free ram, because free ram is doing nothing, whereas cache can be re-allocated as RAM for use by applications if required.

    "Aggressively freeing" inactive RAM (if it is not required) would be simply discarding the contents of cache, which would be a net lose performance wise.

    When you are measuring performance at 40%, is that the total for all cores? It is possible that the app is single threaded, and bottlenecked for CPU on only 1 core.

    Did this app work differently on snow leopard?

    By "the system" do you mean responsiveness within your app, or all tasks on the mac?

    at a guess, i would suspect that your machine is starved for IO. Check activity monitor for disk activity, and check how many IOs per second it is doing and what the throughput is.

    Check your app to see if it can be more aggressive with regards to caching audio in RAM (look for "cache size" or similar preferences) rather than streaming from disk. If your IO is the problem, it could be due to disk fragmentation (reinstall/restore from backup, or defrag) OR simply that you need a faster disk.

    I've noticed massive IO performance improvement between Lion 10.7.3 and 10.7.4, however there may be something wierd with your particular install and perhaps a clean install of 10.7.4 will rectify this.

    If you are running a virus scanner, try disabling it temporarily to see if it is impeding IO performance.

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