Boot Camp disk performance

Discussion in 'Parallels Desktop for Mac' started by j-active, Feb 2, 2007.

  1. j-active


    So, I am finally able to use the Boot Camp partition in Parallels 3150 RC2 by creating a custom configuration. This is a welcome fix. However, the disk performance is so poor it is not usable. The disk operation is so slow that I'm seeing beach balls in OS X when there's context switching in Parallels when doing disk intensive operations. Edit: this does NOT happen when using a virtual disk.

    I'm only getting 26 MBps on reads and an effective throughput of 3.5 MBps on random seek operations. When using a virtual disk (single image, not Boot Camp) I get more than 100 MBps on reads and an effective throughput of > 50 MBps!!!

    1) Is there any way to improve the disk speed when using the Boot Camp partition in Parallels? Is there a special setting that can be specified in the config file?

    2) Is there hope of the virtual disk driver performance improving?

    I haven't really looked, but I have a feeling the the PIO/DMA mode of the drive is probably different between the virtual drive and the physical drive.

    To be clear, I am not talking about the performance difference of the Boot Camp partition when booting over to Boot Camp vs. running in Parallels. Yes, there is a huge discrepency in performance there, but specifically I'm referring to the performance of a virtual disk image vs. a physical Boot Camp partition as the underlying Windows drive in Parallels. Look at the numbers above. There's a 1,000% difference in performance of the virtual drive.

    Parallels, please advise.
    Last edited: Feb 2, 2007
  2. ksenks

    ksenks Parallels Developers

    I think low perfomance isn't because of loading from Boot Camp partition.
    Do you have any VMs worked faster than VM from Boot Camp?

    Try to do this:
    1. Launch Parallels Desktop.
    2. Click on the "Parallels Desktop" menu on Mac menubar, select "Preferences".
    3. Open "Memory" section and make sure that "Reserved Memory Limit" is set to maximum value, this setting indicates the maximum ammount of RAM that VM may take from the host system. Hit "OK" to close "Preferences" window.
    4. Click on the "Memory" link in the main Parallels Desktop for Mac configuration window
    5. Make sure that "Memory Size" setting doesn't exceed "Reserved memory limit", it's better to keep "Memory Size" ammount at the recommended value.
    6. Hit "OK" to close "Configuration Editor"
  3. j-active


    Hi, thanks for the quick reply.

    The overall "feel" whether using a virtual disk or Boot Camp is similar when comparing the CPU. The perceived performance is almost identical whether using a virtual disk or Boot Camp. However, the disk reads are so slow in Boot Camp it's lagging/freezing the OS and causing OS X to react somehow (beachball cursor). This happens often when multitasking under the Boot Camp disk and the freeze stops as soon as the disk light (in the status bar) goes out signifying a disk operation is complete. I can reproduce this almost everytime in Boot Camp. This does not happen at all in a VM on a virtual disk.

    I'm almost positive it's a drive throughput issue related to reading and random seek on Boot Camp disks. I just checked again and I'm getting VERY fast writes on the Boot Camp disk (faster than a virtual disk!) but the reads are incredibly slow (3 MB/s random read/write ops compared to 55MB/s random r/w using a virtual disk). Note: those are random r/w ops, raw read throughput is 120MB/s on the virtual disk and around 27MB/s on the Boot Camp disk.

    The memory is correctly configured (as you suggested) and the amounts are the same on both Boot Camp and the virtual disk.
    Last edited: Feb 2, 2007
  4. j-active


    Ksenks- There is another thread where someone was seeing beachball cursors and the problem was related to the ParallelsToolsCenter and clipboard updating. Is it possible there is a blocking operation in your code that would cause the ParallelsToolsCenter functions to affect the disk drivers or overall execution of the OS code? I killed the ToolsCenter in my client OS and I'm not seeing the cursors which leads me to think you were right --- the drivers are OK and the problem is related to another blocking operation that is freezing the entire OS. The drive lights stay on because the entire OS is blocked (not just a slow disk operation!).

    Just a hunch --- I need to do some more testing. Here was the other thread:
  5. rhind


    Not directly related to your problem, but just to say I have switched from using a disk image to at 48GB NTFS partition on my MBP (160GB drive) and under visual studio 2005, building my project has gone form 8 minutes to 5:15. A large improvement. When booted directly with BootCamp, I see 3:45 but BootCamp appears to be much quicker than using a disk image (although the 8 minutes was timed under 3120 so perhaps it is just general performance improvements from 3120 to 3150). (I have my caching policy set to OS X)


  6. j-active



    Thanks for posting those numbers Russell. They are interesting to see.

    I did some quick testing and found Boot Camp to be MARGINALLY faster than an image for writes, MUCH slower for reads, and MUCH slower for random access. The performance improvements from later builds and the faster writes could explain your timing results.

    I'd be interested in seeing the results if someone else can measure read/write/random performance of a virtual disk vs. Boot Camp.

    An update after more testing on the original issue: I have not been seeing the beach ball wait cursors at all since killing the tools center. The disk performance issue was a confounder, because the entire OS seems to be blocked when the clipboard code syncs and OS X freaks out temporarily.

    Overall, I'm pretty happy with this release. Things are working and I'm finding myself getting stuff done!
  7. Gannet


    I've been using Parallels for a while and been reasonably happy with the performance but after switching to using the Boot Camp partition (in about mid-Jan) I've found the performance is shocking. I never did any tests or investigations into the problem but from what you're saying, j-active, I can just kill the Tools and it'll run fine (albeit without the Tools)?
    Can we get more word from the Parallels team here? Is this an issue which can be fixed or would I really be better off using a virtual drive?
  8. arsoucy


    Did this thread just die? I've been using Parallels for quite awhile now on my Macbook and I've been quite happy with the performance. I just upgrade to a Mac Pro and decided to go the Boot Camp route because I want to be able to Pro/ENGINEER at full speed from time to time. I was shocked with how terrible the performance was using the Boot Camp route. It takes forever to start up and log in and using it so slow. Way different than it was on my MacBook using a virtual drive. Any thoughts? I can live with it but I miss the old performance.

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