Which OS uses least system memory?

Discussion in 'OS X El Capitan (10.11)' started by jetlife2, Nov 18, 2015.

  1. jetlife2 macrumors regular

    jetlife2

    Joined:
    Apr 18, 2004
    Location:
    Cincinnati, Oh
    #1
    Are there any articles or tests published comparing the amount of RAM used by various versions of the OS? For example Mavericks vs Yosemite vs El Capitan?

    Obviously this question only refers to a system without any apps running. In other words, which OS leaves the most available for user apps.

    Some Macs have only 4GB hardwired, so this question is interesting as it shows the headroom available before starting to page the data.

    Thanks if anyone can point to an actual study with data, vs anecdotes.
     
  2. Rodan52 macrumors regular

    Rodan52

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    Location:
    Melbourne, Australia and Bali, Indonesia
    #2
    jetlife2, you have asked a rather complex question as there are a few ways of measuring memory usage. Anecdotally I can say that Yosemite and El Capitan are more "memory" efficient than Mavericks. If you are asking which OS will have less spinning "beach balls" that is different as that is dependant on CPU speed as well as RAM and the type of drive in use HDD or SSD. The best benchmark for measurement is Memory Pressure. Here is a pic of my Memory usage running this browser only.


    Screen Shot 2015-11-19 at 14.44.04.png .
    And here is the same system running running this browser, MS Word, Calendar and Photos.
    Screen Shot 2015-11-19 at 14.50.58.png
    You can see the difference is not great but notice background tasks and kernel_task changes. What I am saying is that your question cannot be answered in the simple terms of one value. I am running El Capitan with a
    2.5 GHz Intel Core i5 processor and 4 GB 1600 MHz DDR3 (RAM) and it works just fine and to my mind better than Mavericks but about the same as Yosemite.
     
  3. Evren Carven macrumors regular

    Evren Carven

    Joined:
    Dec 16, 2014
    #3
    Yes, it needs professional testing to get the actual data. For general user, you only need to know system requirements. For example:
    OS X El Capitan, General Requirements: 2GB of memory. Yosemite/Mavericks, also 2 GB of RAM.
     
  4. jetlife2 thread starter macrumors regular

    jetlife2

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    Apr 18, 2004
    Location:
    Cincinnati, Oh
    #4
    Thanks both

    I am going to build a clone drive with each OS and boot from there. It won't be speedy but it should give an accurate answer to this specific question. I was hoping someone had already done it. Cheers
     
  5. dogslobber macrumors 68020

    dogslobber

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    #5
    El cap and Yosemite compress unused memory before paging when memory is low. This will be refined in el cap more so than Yosemite so el cap s likely best.
     
  6. simonsi macrumors 601

    simonsi

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    Auckland
    #6


    Virtual memory, memory compression and SSDs render this question really obsolte. FYI I have pushed my 4GB MBA on Yosemite and El-Capitan to well over 8GB virtual with no noticeable performance hit. And that is the test, not chasing some number.
     
  7. jetlife2 thread starter macrumors regular

    jetlife2

    Joined:
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    Location:
    Cincinnati, Oh
    #7
    The reason for the question was that I have a Macbook Pro with 4GB and no SSD. I agree with the comment that with an SSD it is not so important...after all that is just more RAM configured as a drive, so "virtual memory" is a misnomer. My main desktop machine has an SSD and I'm not impacted there.

    But, on the MBP which hits a traditional HD for virtual memory, the slowdown is severe, so for that type of machine it is a useful question.
     
  8. jetlife2 thread starter macrumors regular

    jetlife2

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    Location:
    Cincinnati, Oh
    #8
    So I did some testing. Disclaimer: There are many variables. I tried to eliminate the obvious ones. Your results will be different. No warranty expressed or implied.

    System Memory used, running only Activity Monitor:

    OS GB Used
    10.7.5 2.74
    10.8.5 1.80
    10.9.5 3.10
    10.10.5 2.70
    10.11.1 3.50

    Method: clean install to empty Firewire partition. Boot in Safe Mode. Typical result from several starts.

    Obviously there are other pros and cons to each of these OS's and this is just one aspect. Your weighting of this part of the story will be different depending on your situation. Mine too. I'm putting this data out here just for interest. Feel free to repeat the test and post your data.
     
  9. dogslobber macrumors 68020

    dogslobber

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    #9
    data transfer rate for physical memory is at least 10x faster than the fastest SSD today. To say there is "no noticeable performance hit" is a little premature.
     
  10. simonsi macrumors 601

    simonsi

    Joined:
    Jan 3, 2014
    Location:
    Auckland
    #10


    RAM is not the same as even an SSD drive, they are fundamentally different and you cannot execute processes in SSD storage. RAM is still WAY faster than even SSDs as well but even if SSDs wer AS fast, it doesn't remove the advantage of virtual memory and RAM compression.

    Virtual memory is not a misnomer. Worth you finding out what these terms actually mean.
     
  11. simonsi macrumors 601

    simonsi

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    Jan 3, 2014
    Location:
    Auckland
    #11
    i meant to the use in practical use, everyone waits for an HDD system, with an SSD, even on processes waiting for the SSD it isn't so noticeable.
     

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