Apple's OS X Mountain Lion reportedly hindering MacBook Air 802.11ac speeds

Posted:
in Current Mac Hardware edited January 2014
One of the major upgrades found in Apple's latest MacBook Air is the inclusion of 802.11ac Wi-Fi, but a discovery on Monday appears to show an issue in OS X 10.8 Mountain Lion is hampering the laptop from reaching peak data transfer speeds.

MBA


In a review of the mid-2013 13-inch MacBook Air, Anand Lai Shimpi of AnandTech found real world 802.11ac file transfer speed to be artificially slowed by an apparent software issue in OS X Mountain Lion.

After finding speeds hitting a cap of 21.2MBps or 169.6Mbps over 802.11ac, much lower than the 533Mbps throughput seen with network testing tool iPerf, Shimpi narrowed down the problem to Apple Filing Protocol (AFP) and Microsoft's Server Message Block (SMB). Further investigation showed OS X does not scale TCP windows to the appropriate size, thus limiting the performance of the newly implemented 11ac protocol.

"The bad news is that in its shipping configuration, the new MacBook Air is capable of some amazing transfer rates over 802.11ac but you won?t see them when copying files between Macs or PCs," Shimpi wrote. "The good news is the issue seems entirely confined to software. I?ve already passed along my findings to Apple. If I had to guess, I would expect that we?ll see a software update addressing this."

A separate report from Ars Technica claims an 802.11ac-enabled MacBook Air running Windows 8 in Boot Camp will reach higher file transfer speeds than Apple's own operating system. While transferring files in Windows is relegated to Microsoft's SMB protocol, the publication saw speeds 9 percent faster than OS X over Ethernet, 30 percent over 802.11n and 218 percent faster on 802.11ac.

The issue also presents itself in the Developer Preview build of OS X Mavericks, suggesting the TCP limitation was not purposely instituted.

Comments

  • Reply 1 of 16


    Mavericks we have a bogey on our 3:00. Don't worry Goose, I've got him. Looks like a dated SMB protocol. Splash one old SMB Goose! Yeehaw!!! I'm going vertical with afterburners Goose!!! You are the best Mavericks!!!

  • Reply 2 of 16
    tallest skiltallest skil Posts: 43,399member
    Mavericks we have a bogey on our 3:00. Don't worry Goose, I've got him. Looks like a dated SMB protocol. Splash one old SMB Goose! Yeehaw!!! I'm going vertical with afterburners Goose!!! You are the best Mavericks!!!

    And when it gets home safely, it can buzz the tower.
    1000
  • Reply 3 of 16
    gtrgtr Posts: 3,231member

    Quote:

    Originally Posted by GadgetCanadaV2 View Post


    Mavericks we have a bogey on our 3:00.



     


    Roger, Gadget, I have your bogey.


     


    Engaging...


     


    Lining up for the shot...


     


    I'm almost there...


     


    10 more mbps then I've got him...

  • Reply 4 of 16
    djrumpydjrumpy Posts: 1,116member
    You do realize Apple is ditching AFP for SMB right? ;)

    That said, I see a substantial perk to my speeds when going to Mavericks (from 19-20MB/s to 36MB/s).

    From what I recall from WWDC, the indicated that Mavericks will still support AFP, especially when talking to AFP clients, but the default will be SMB going forward.
  • Reply 5 of 16
    correctionscorrections Posts: 1,172member
    djrumpy wrote: »
    You do realize Apple is ditching AFP for SMB right? ;)

    That said, I see a substantial perk to my speeds when going to Mavericks (from 19-20MB/s to 36MB/s).

    From what I recall from WWDC, the indicated that Mavericks will still support AFP, especially when talking to AFP clients, but the default will be SMB going forward.

    But the issue isn't AFP vs SMB; under either protocol, it appears OS X isn't achieving the expected throughput.

    It appears the issue is a software TCP network setting in OS X that is not optimal when using 802.11ac wifi, preventing file sharing from benefitting from the extra boost in speed, making either protocol slower than it should be.
  • Reply 6 of 16
    djrumpydjrumpy Posts: 1,116member
    But the issue isn't AFP vs SMB; under either protocol, it appears OS X isn't achieving the expected throughput.

    It appears the issue is a software TCP network setting in OS X that is not optimal when using 802.11ac wifi, preventing file sharing from benefitting from the extra boost in speed, making either protocol slower than it should be.

    I never stated it was. I just stated that Apple was adopting SMB as the default starting in 10.9.
  • Reply 7 of 16
    lkrupplkrupp Posts: 6,294member


    This is the last straw. I'm dumping Macs and OS X and moving to a real operating system. I just don't know what that is right now.

  • Reply 8 of 16
    ipilyaipilya Posts: 180member
    So does this problem also exist on the Airport Extreme?
  • Reply 9 of 16
    djrumpydjrumpy Posts: 1,116member
    The problem is not due to the Extreme, or any of the Airport products. it's just a bug in the OS, and sounds like it can be easily fixed.
  • Reply 10 of 16
    drblankdrblank Posts: 3,383member
    I'm sure Apple might release an update to Mountain Lion to address this in 10.8.5 which is starting to be seeded. Does any developer know if this is happening with 10.8.5?
  • Reply 11 of 16
    djrumpydjrumpy Posts: 1,116member
    Probably not soon enough to hit a build yet, but certainly do-able given enough time before 10.8.5 is released. It just depends on where the problem lies, and how easy it is to implement a fix.
  • Reply 12 of 16
    rcoleman1rcoleman1 Posts: 153member


    Apple will certainly fix this.

  • Reply 13 of 16
    thepixeldocthepixeldoc Posts: 2,257member
    rcoleman1 wrote: »
    Apple will certainly fix this.

    No they won't...ever...never...! Apple is surely DOOOOOOMED™ this time!
    lkrupp wrote: »
    This is the last straw. I'm dumping Macs and OS X and moving to a real operating system.* I just don't know what that is right now.

    Me too! Even my Win'95 box was better than THIS!
    djrumpy wrote: »
    The problem is not due to the Extreme, or any of the Airport products. it's just a bug in the OS, and sounds like it can be easily fixed.

    What part of no, never or ever... do you not understand?!

    Doomed I Say! :no:

    /s

    * Try this with a Windows RT tablet and all your dreams will...................???!!!! :rolleyes:
  • Reply 14 of 16
    djrumpydjrumpy Posts: 1,116member
    LOL ;)
  • Reply 15 of 16
    If I had to guess, I would say that Apple knew full well about the speed limitation but decided to ship their tried and tested TCP stack with the initial release of the Macbook Air in order to meet their deadlines and always had a plan to address the issue with a future version of Mountain Lion or Mavericks.

    One thing that Apple does extremely well is networking software. After trying routers and software from various vendors, I ended up going all Apple and now enjoy extremely fast and reliable networking and almost never have to reset my routers. Compare that to the weekly and sometimes daily resets required of all routers from other brands. Also even though I have been a software developer for more than 30 years, I have never been able to get Windows networking to work correctly between different versions of that operating system or between Windows and Mac. It is like they are on completely different networks. This may explain why I am willing to give Apple the benefit of the doubt when it comes to their technical decisions.
  • Reply 16 of 16
    hezetationhezetation Posts: 674member
    GrangerFX wrote: »
    If I had to guess, I would say that Apple knew full well about the speed limitation but decided to ship their tried and tested TCP stack with the initial release of the Macbook Air in order to meet their deadlines and always had a plan to address the issue with a future version of Mountain Lion or Mavericks.

    One thing that Apple does extremely well is networking software. After trying routers and software from various vendors, I ended up going all Apple and now enjoy extremely fast and reliable networking and almost never have to reset my routers. Compare that to the weekly and sometimes daily resets required of all routers from other brands. Also even though I have been a software developer for more than 30 years, I have never been able to get Windows networking to work correctly between different versions of that operating system or between Windows and Mac. It is like they are on completely different networks. This may explain why I am willing to give Apple the benefit of the doubt when it comes to their technical decisions.

    Putting an APC between your router & the power outlet will usually fix the need to reboot often, unless your using linksys. I've had just about every type of router there is & find Netgear to be more reliable than Apple, but not by much. I use an AE for the Time Machine feature & iCloud support but now that Netgear has support for TM & it's own cloud sharing feature my future purchases may change.

    As for networking, I'll take OSX over Windows any day for anything network related, for sure it is far superior to Windows in this regard.
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