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
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  • marc1000 - Monday, January 4, 2010 - link

    Indeed, I want an Atom+ION, but it has not yet come to public availability in Brazil. And Intel is killing ION with the new Atoms, so I believe I won't ever see a Atom+ION board here, because the stores will only launch only the "newer" Atom boards (that is, IF they even launch it...)
  • efficientD - Saturday, January 9, 2010 - link

    The other problem with and atom setup is the low cost no L3 cache Athalons. With a decent 785G mainboard, you can get much better performance in only a slightly bigger package for about the same HTPC money. That is the direction I would go if I could build an HTPC right now.
  • IntelUser2000 - Monday, January 4, 2010 - link

    The reason for high idle and in some way, high load power is due to the Asus board. Not only that, but the H57 chipset.

    The Intel H55 mobo will lower power consumption enough to get it below the i5 750 and i7 860.
  • Kaleid - Monday, January 4, 2010 - link

    Would these be chips on would dare to overclock considering the foxconn socket problems that has been reported here @ anandtech?
  • Zool - Monday, January 4, 2010 - link

    Its quite confusing now, with 9 desktop and 11 mobile i-xxx cores now. Not a single digit shows core numbers or the gpu on the new 32nm cpus.
    Actualy its a total mess now for a average user.
  • marc1000 - Monday, January 4, 2010 - link

    I second your opinion!!! Perhaps Intel hired some marketing folks from Nvidia!!! =D
  • Harry Lloyd - Monday, January 4, 2010 - link

    So which chip is responsible for HDMI Audio - the CPU, or the H5x chipset?
    Can we get HDMI audio support with a Lynnfield CPU?

    And one other thing - I assume we can use HDMI audio without haeving to use the integrated GPU (for display) when we have a PCI-E card?
  • DigitalFreak - Monday, January 4, 2010 - link

    The GPU on the processor.
  • Alberto - Monday, January 4, 2010 - link

    The main problem is the Motherboard, likely an early sample not much optimized. Both Xbit Lab and The Tech Report have found a lower idle system power consumption in the new Intel plataform versus the Lynnfield solution. Maybe This article needs of a fast update :-)
  • Alberto - Monday, January 4, 2010 - link

    The italian site have discovered even better results. Over an Intel DH55TC motherboard this new cpu is IMPRESSIVE at idle.
    Intel seems right again.

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