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Software Slowing Some Wi-Fi File Transfers on New MacBook Air

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Original poster
Apr 12, 2001
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Networking code in OS X Mountain Lion is slowing down file transfers over the Apple Filing Protocol (AFP) and Microsoft's Server Message Block (SMB), according to examinations done by both Ars Technica and AnandTech.

The issue affects the new MacBook Air models that come equipped with the 802.11ac Wi-Fi technology. The new MacBook Air and Apple's new AirPort Extreme base station are the first Apple products to use the new Wi-Fi technology.

Anandtech discovered that the TCP window size for file transfers in OS X was too small to reach the potential throughput on many file transfers, slowing data transfers from a potential 533Mbps down to 170Mbps.
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. 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.
Click to expand...
Ars Technica confirmed AnandTech's findings, and went a bit further. The site discovered that when running Windows 8 in Boot Camp, the new MacBook Air saw file transfer speeds significantly higher than under a comparable setup in OS X Mountain Lion.
Some variation between the two operating systems is to be expected. They're very different under the hood, after all, and Microsoft's strong commitment to the enterprise (and the file servers therein) makes it unsurprising that Windows' file transfer speeds are generally a bit faster than OS X's. However, the discrepancy between the Windows 802.11ac speeds and OS X speeds is too large to be explained away by networking optimizations alone. Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, but it's 218 percent faster over 802.11ac.
Click to expand...
Ars' OS X wireless setup saw transfer speeds of 21.71MB/s on SMB, and 47.26MB/s on a comparable Windows 8 setup under Boot Camp.

The issues also exist under the developer beta of OS X Mavericks, but both sites expect Apple to release a software fix for OS X that will solve the file transfer issues.

Article Link: Software Slowing Some Wi-Fi File Transfers on New MacBook Air
 
Article Link
https://www.macrumors.com/2013/06/24/software-slowing-some-wi-fi-file-transfers-on-new-macbook-air/
L

locoboi187

macrumors 6502a
Oct 3, 2012
711
375
Darn I still want an ac device for my new time capsule! I wanna see what the fuss is about when its put to its proper power!
 
ValSalva

ValSalva

macrumors 68040
Jun 26, 2009
3,783
259
Burpelson AFB
Not a big surprise. New hardware often has driver/software problems. No need to return new MacBook Airs. They will be fixed in a software update ;)
 
star-affinity

star-affinity

macrumors 68000
Nov 14, 2007
1,928
1,219
ValSalva said:
Not a big surprise. New hardware often has driver/software problems. No need to return new MacBook Airs. They will be fixed in a software update ;)
Click to expand...

One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?
 
parapup

parapup

macrumors 65816
Oct 31, 2006
1,291
49
star-affinity said:
One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?
Click to expand...

Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)
 
3

3282868

macrumors 603
Jan 8, 2009
5,281
0
parapup said:
Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)
Click to expand...

How quickly things change (sigh) :eek:
 
CWallace

CWallace

macrumors G5
Aug 17, 2007
12,006
10,684
Seattle, WA
One would think these would have been caught in testing and development, however...

Unless they were all on a special "802.11ac" build of 10.8.4 that was meant to be released with the MBA, but for some reason was not (or perhaps testing was done on 10.8.5)?

As noted, I expect 10.8.5 will fix it or there will be a special patch of 10.8.4 for MBA users.
 
D

dakwar

macrumors 6502
Nov 2, 2010
322
17
MacRumors said:
Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, ...
Click to expand...

Wow. I do a lot of Mac-to-Mac, Mac-to-Windows, and Windows-to-Windows transfers. Mac-to-anything transfered always seemed slower to me but I always thought I was imagining it. Am feeling disappointed now with the Mac's performance here. 30% over 802.11n is a large difference.
 
ValSalva

ValSalva

macrumors 68040
Jun 26, 2009
3,783
259
Burpelson AFB
star-affinity said:
One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?
Click to expand...

Yes, one would think that. Despite owning the stack Apple still has its share of problems.

NewbieCanada said:
For all we know, it's already been taken care of in Mavericks.
Click to expand...

Unfortunately the problem also is in the Mavericks developer preview :eek:
 
Cubert

Cubert

macrumors regular
Apr 30, 2005
150
0
"Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, but it's 218 percent faster over 802.11ac."

Unacceptable for any protocol. Apple needs to correct this. There is no reason that a Unix based OS should be slower than Winblows in file transfer speeds.
 
kd5jos

kd5jos

macrumors 6502
Oct 28, 2007
432
144
Denver, CO
parapup said:
Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)
Click to expand...

One case = delusions of integration
Hundreds of cases of fail because of lack of integration = ???

I think you need to return your logic unit, it appears to be the old Pentium 100 type with the math error in it.
 
M

MikhailT

macrumors 601
Nov 12, 2007
4,582
1,325
star-affinity said:
One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?
Click to expand...

parapup said:
Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)
Click to expand...

Integration doesn't mean there wouldn't be bugs. This is a software issue that can be fixed in a future update. It only affects SMB/AFP. The rest works fine.

NewbieCanada said:
For all we know, it's already been taken care of in Mavericks.
Click to expand...

It hasn't been fixed in Mavericks according to Anand.

Cubert said:
"Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, but it's 218 percent faster over 802.11ac."

Unacceptable for any protocol. Apple needs to correct this. There is no reason that a Unix based OS should be slower than Winblows in file transfer speeds.
Click to expand...

It's just a bug in the TCP window sizing system for both AFP/SMB stacks. It's not resized to 256KB properly. Once they fix the bug, it'll just be normal fast.
 
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J

Jibbajabba

macrumors 65816
Aug 13, 2011
1,024
5
parapup said:
Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)
Click to expand...

Don't be silly. Ever read the non-iOS cell forum? True fanboys will defend it no matter what ... Watch this space :p
 
Pakaku

Pakaku

macrumors 68040
Aug 29, 2009
3,134
4,440
star-affinity said:
One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?
Click to expand...

I'd think one would think that, since Apple makes both, they can deal with the problem quicker than if they didn't have that control...
 
phoenixsan

phoenixsan

macrumors 65816
Oct 19, 2012
1,342
2
Sighs....

being a software issue, that can be fixed via a Software Update. Dont like a shinny piece of software with network bottlenecks......:mad::eek:


:):apple:
 
W

WordMasterRice

macrumors 6502a
Aug 3, 2010
734
100
Upstate NY
MikhailT said:
It's just a bug in the TCP window sizing system for both AFP/SMB stacks. It's not resized to 256KB properly. Once they fix the bug, it'll just be as fast as Windows.
Click to expand...

No it won't it says right in the article that transfers are slower on OSX and that isn't the particular issue here. Resizing the window is only going to get it up to normal levels of slower than Windows, not up to Windows speed.
 
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