Apple's 15-inch Core i5 MacBook Pro: The One to Get?by Anand Lal Shimpi on April 14, 2010 10:38 PM EST
No AES-NI Support in OS X?
One of the features of Arrandale (and all other Westmere derived architectures) is support for AES-NI. The six instructions that fall under the AES-NI umbrella can accelerate encryption and decryption operations.
Microsoft's full disk encryption feature in Windows 7, BitLocker, is AES-NI accelerated. Simply upgrading to a supported Core i5 or i7 processor gives you better disk performance with BitLocker turned on.
While I'm still waiting for Apple to get back to me on a number of questions, I decided to see if FileVault, OS X's encryption system was AES-NI accelerated as well.
I ran XBench's disk tests on an encrypted home directory and then again on a completely unencrypted portion of the drive. If Apple takes advantage of the Core i5's AES-NI I should see a smaller drop in performance on the new MacBook Pro compared to the old one:
|FileVault Disk Performance Comparison|
|Sequential Read (256KB)||Sequential Write (256KB)||Random Read (4KB)||Random Write (4KB)|
|Core 2 Duo MacBook Pro - FV Off||172.5 MB/s||127.1 MB/s||10.9 MB/s||134.1 MB/s|
|Core 2 Duo MacBook Pro - FV On||79.5 MB/s||61.9 MB/s||6.8 MB/s||67.8 MB/s|
|Core i5 MacBook Pro - FV Off||175.1 MB/s||160.0 MB/s||21.5 MB/s||112.7 MB/s|
|Core i5 MacBook Pro - FV On||80.5 MB/s||66.6 MB/s||13.2 MB/s||61.0 MB/s|
And it looks like we have no AES-NI support in FileVault at least. It's not terribly surprising. Apple usually takes a while to implement new features enabled by hardware changes. Remember how long it took Apple to get GPU accelerated video decoding?
These numbers do tell us something else entirely though: the new MacBook Pro appears to offer better SATA performance.
Not too long ago I published a quick look at 6Gbps SATA controller performance and concluded, among other things, that Intel's SATA controllers are quite good. The numbers above support that theory as disk performance has gone up considerably compared to last year's NVIDIA based MacBook Pro. While random write speed dropped a bit, random read and sequential write performance jumped up significantly.
This is quite noticeable with a SSD but less of a problem with a hard drive. Needless to say Apple's return to Intel is a good thing, especially because we didn't have to give up NVIDIA's graphics.