AES-NI: Much Faster Encryption & Bitlocker Performance

Westmere (and thus Clarkdale) adds some new instructions to x86, although the big expansion comes with AVX and Sandy Bridge next year. Westmere gets six new encryption/decryption instructions. The group of instructions accelerate AES (Advanced Encryption Standard) and are thus referred to as AES-NI.

Many businesses require that all corporate PCs have the contents of their hard drives encrypted through the use of software like Bitlocker that comes with Microsoft Windows 7. These sorts of applications can be accelerated by AES-NI and to show the potential benefit I dug up a test I did while preparing for one of our SSD articles several months ago.

If you turn on Bitlocker in Windows 7 there's an immediate and measurable impact to performance. Disk performance generally drops by a noticeable amount and actual application usage performance drops by a smaller amount. Every write to the disk has to be encrypted first so there's some obvious CPU overhead. Clarkdale should reduce that overhead significantly as the common encryption operations are now hardware accelerated.

To test this I ran three tests. I first ran PCMark Vantage's HDD suite on my Windows 7 testbed SSD (an OCZ Summit) on a Core i5 661, then encrypted the drive using Bitlocker and ran the same test on the same processor. For the last test I swapped out the i5 661 for a Lynnfield based Core i5 750 (no AES-NI) and re-ran the HDD test. The results below were quite promising:

Processor PCMark Vantage HDD % of Unencrypted Performance
Clarkdale - Unencrypted 16713  
Clarkdale - Bitlocker Encryption 13785 82.5%
Lynnfield - Bitlocker Encryption 11744 70.3%

 

There's a definite benefit to Clarkdale's AES-NI instructions. There's still a performance hit from enabling Bitlocker, but it's not nearly as great as on Lynnfield and other architectures that don't have AES-NI support. With a smaller decrease in I/O performance from enabling full disk encryption, there's also a smaller hit to application performance as well. This is huge for corporate desktops/notebooks.

Most of those machines aren't quad-core encoding monsters; they use dual-core processors. The upgrade from Core 2 seems like it'd be worth it, or at least AES-NI will probably keep AMD out of the running for consideration.

Intel HD Graphics: A Lot Better ASUS Saves the Day: Simulated Core i3s & The Test
POST A COMMENT

93 Comments

View All Comments

  • ssoussi - Wednesday, September 22, 2010 - link

    Check the Quick Reference Guide to Intel® HD Graphics on the official website:
    http://software.intel.com/fr-fr/articles/quick-ref...
    Reply
  • kumargupta9 - Wednesday, December 22, 2010 - link

    I was doing a research on i3 vs. i5 vs. i7.. found many articles which this one as the best. Also found the following also useful. http://binaryday.com/2010/12/09/intel-core-i3-vs-c... Reply
  • Hothead - Saturday, June 11, 2011 - link

    hey...
    i'm using dell N series system with 320 gb hard-disk,4GB Ram with grapic card nvidia 9500 GT installed but d problem started when i changed processor dual core to core 2 duo...& added 500 gb sata hard-disk...now my mother botherboard is crashed ...now i'm thinking 'bout i5 processor wid h55 mother board ...plz guide me...what should i do 2 upgrade my system so tht i can have a speedy pc with speed features & do support d games ...or don't ever again crash or something like tht...
    Reply

Log in

Don't have an account? Sign up now