Optimum Memory settings

Discussion in 'Parallels Desktop for Mac' started by dmgwork, Jul 8, 2006.


How much memory do you have allocated ?

Poll closed Aug 7, 2006.
  1. 1024

  2. 768

  3. 512

  4. < 512

  1. dmgwork


    please use new thread for poll Optimum Memory settings

    Has anyone doen any testing to determine what is the best setting for ram in Parallels. I know they dont recomend setting it too high, and have seen a report that states at 800mb it gets much slower.

    Is this something that parallels is planning on addressing?

    If anyone has done some testing I would appreciate finding out what they have observed.
    Last edited: Jul 8, 2006
  2. mtnbkr


    Parallels recommended 1500 for my install, I'm running at 512 and it seems to be working pretty well.
  3. boogie


    i was intrigued by this post, so i ran some quick tests...

    hardly scientific or complete, but i just ran the passmark performance test 6.0 cpu and memory benchmarks several times with 512, 768, 1024MB allocated to a WinXP Pro/SP2 installation on a mac mini with 2GB of physical ram

    the cpu mark and mem mark aggregate results were within 1-2% of each other for each configuration across runs.... so from the perspective of the raw memory and cpu performance of the underlying virtualized hardware, there is no significant difference within this range of allocation.

    since there seems to be no difference in performance from the perspective of what the GUEST OS is able to get from the virtualization infrastructure it doesnt look like parallels adds more overhead as you increase the VM GUEST OS RAM allocation (at least when you still have plenty of available resources on the HOST)...this is likely the source of the advice you might have heard on allocation of resources....i.e. you dont want to allocate 90% of your overall HOST resources to the GUEST VM's as the HOST OS itself (which has to run all these VM's) will starve. i'm betting that if you heard 800MB was a top end recommendation it was for a HOST with 1024MB overall RAM.

    i havent run any applcation specific benchmarks, but i would expect that as on bare metal, if a GUEST based application is able to take advantage of more RAM, it will perform better under 1024MB than under 512MB as long as the HOST itself has adequate resources.

    Last edited: Jul 8, 2006
  4. unused_user_name


    This would be a better poll if it also included the total amount of system memory.

    Allocating 512Mb when your system has 2Gb of RAM and allocating 512Mb when your system has only 512Mb of RAM are two completely diffrent environments.

    Also, the performance issues I've seen have all been on the Mac side in other applications while Parallels is running. I have yet to see Parallels itself slow down.
    Last edited: Jul 8, 2006
  5. dmgwork


    Thanks for your information, Based on the feedback, i created a new posting which has both the mac memory and the amount allocated to Parallels
  6. wesley


    Parallels has 384MB allocated, and the VM with Windows 2000 SP4 got 256MB. Works like a champ.
  7. netdog


    I have allocated 256MB and it runs great. Really fast. As I have 2GB of RAM, I could easily allocate more, but I find no reason to do so.
  8. seven


    I have 2GH white macbook with 2GB memory. Parallels by default set "Reserved Memory Limit" to 1612MB. With that, not only osx was sluggish (although usable, except virtue taking 3-5sec to change between desktops ) but also xp/sp2 was unusably slow. So I tested various sizes (256, 384, 512, 640, 748MB) of "Reserved Memory Limit" along with "Recommanded RAM Maximum Size" for the guest os, xp/sp2. Strangely enough, anything but 512MB of "Reserved Memory Limit" gave me the same problem---sluggish osx (not to mention virtue) and unusably slow xp/sp2.

    Yet another problem I had was that, once osx became slow, it remained slow even after parallels quit. Only rebooting brings osx back to normal. I don't know how "Reserved Memory Limit" works in parallels. However, if parallels actually locks up the "Reserved Memory Limit" amount of memory at launch, my suspicion is that it does not properly release the locked-up memory when it quits. Just a random guess...

    Anyway, I settled with 512MB(Reserved Memory Limit)-412MB(Recommanded RAM Maximum Size) combination, but am desperately looking for a way to increase the memory allocation for the guest os for my memory intensive works.

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