SSD performance under bootcamp crippled? Read only 300MB/sec

Discussion in 'MacBook Pro' started by Philflow, Jun 28, 2011.

  1. Philflow, Jun 28, 2011
    Last edited: Jun 28, 2011

    Philflow macrumors 65816

    May 7, 2008
    I've got a Vertex 3 120GB in my MBP 2011 13". Read speed (with 0 fill data) under bootcamp is only 300 MB/sec while it should be getting 550 MB/sec.

    In every benchmark (CDM, ATTO, AS-SSD) sequential read is <300 MB/sec.

    Does anyone know why?

    Is anyone getting better SSD performance in bootcamp?

    Edit: I think I found the answer: IDE vs. AHCI:
  2. wikus macrumors 68000


    Jun 1, 2011
    Planet earth.
    If youre on a 2010 Macbook Pro, youre using SATA which is limited to 3Gbit speeds, although that should still be 375Mbp/s (3000mb/8=375mb).
  3. Philflow, Jun 28, 2011
    Last edited: Jun 28, 2011

    Philflow thread starter macrumors 65816

    May 7, 2008
  4. Timur macrumors 6502a


    Oct 14, 2008
    By default Bootcamp only uses IDE drivers instead of AHCI. You need to do a hack that changes the value of a sector on the MBR. Once done you cannot put the MBP to sleep on Bootcamp anymore.

    Furthermore it depends on which AHCI driver you are using (Intel vs. MSAHCI) and then it depends on whether Link Power Management (LPM) is active or not (Registry hack for Intel drivers, "High Performance" power-profile for MSAHCI to turn it off).

    Last but not least CPU power-saving features have a considerable impact, both on real performance and on the measurements. Run something like Prime95 and try the benchmark again, results will change.

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