FileVault Performance

With Lion sporting a more usable version of FileVault I was curious about its performance impact. I'd enabled FileVault on my personal machine and subjectively felt a performance impact, but I needed to quantify it. I put together a number of tests to do just that.

For all of these tests my test platform is a 15-inch MacBook Pro with a 2.2GHz Sandy Bridge Core i7 from early 2011 with an Apple branded 256GB SSD. In these tests I was primarily concerned with two things: how performance is affected, and what sort of extra load FileVault encryption places on the CPU.

Our first test is a simple file copy. I've got a directory of 2200MB worth of RAW files from a Nikon D700. I copy the folder from the SSD to the same SSD and report performance in MB/s:

FileVault Performance - 2200MB File Copy (MB/s)

With FileVault enabled we take a 24% performance hit, hardly insignificant. Average CPU utilization during the file transfer actually dropped with FileVault enabled from 8.5% to 4.5%. I suspect the reason for the drop was the slower overall transfer rate. It would appear that FileVault, at least on a quad-core Sandy Bridge CPU has absolutely no overhead here. Given that Apple near-universally uses AES for symmetrical encryption, it's reasonable to assume here that FileVault is taking advantage of the AES-NI instructions on Intel's Core-i series of processors.

Our next test tested one of Lion's new features: threaded conversations in Mail. We timed how long it took to launch Mail and open a single email thread with 42 replies. If you've used OS X Mail in the past you'll know that CPU utilization goes insane if you're working on a thread with dozens of replies. The same is definitely true for threaded conversations in Lion.

FileVault Performance - Open 42 Reply Email Thread - Time in Seconds

Thanks to the MacBook Pro's SSD both setups complete this task pretty quickly. There is a penalty associated with FileVault though - around 9% in this case. Peak CPU utilization was similar on both systems, 100% of four threads on the eight thread Core i7.

I grabbed a screenshot of the CPU utilization graph in Activity Monitor during this test for both setups:


CPU Utilization: No Encryption (left) vs. FileVault Enabled (right)

While the two vary slightly, you can see that overall CPU utilization appears to be similar regardless of whether or not encryption is enabled.

Our third test is actually one of our standard OS X CPU benchmarks - we time the import of 203 RAW images into iPhoto. This task is impacted by both CPU and I/O performance:

FileVault Performance - iPhoto Import - Pictures per Minute

Despite the I/O dependency, there's virtually no performance impact to enabling FileVault here.

Our final tests are raw I/O tests using Quickbench. I focused on 4KB and 8KB random read/write since those are the most common transfer sizes for random file access. And for sequential operations I focused on 128KB transfers, again optimizing for common sizes.

FileVault Performance - Quickbench 4KB Random Read (MB/s)

FileVault Performance - Quickbench 4KB Random Write (MB/s)

FileVault Performance - Quickbench 8KB Random Read (MB/s)

FileVault Performance - Quickbench 8KB Random Write (MB/s)

FileVault Performance - Quickbench 128KB Sequential Read (MB/s)

FileVault Performance - Quickbench 128KB Sequential Write (MB/s)

Overall the hit on pure I/O performance is in the 20 - 30% range. It's noticeable but not big enough to outweigh the benefits of full disk encryption. Note that under OS X there's still no way to take advantage of SSD controllers with FDE like the SF-1000/2000 series and the Intel SSD 320.

FileVault Safari, iChat, TextEdit, Preview, QuickTime X
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  • grahamperrin - Thursday, July 28, 2011 - link

    Primarily FAO the AnandTech reviewers

    Thank you for a very timely and useful review of FileVault 2.

    The following microblog conversation links to an overview (work in progress) with some unanswered questions. Comments will be greatly appreciated.

    http://identi.ca/conversation/77065575#notice-7963...

    — OpenID enabled, I will welcome contributions in the Identi.ca area.
    Reply
  • nardreiko - Tuesday, August 02, 2011 - link

    And it is a big problem!

    The removal of Expose and Rosetta are big reasons not to "upgrade" for me both now and for the foreseeable future.

    A lot of other things are clunky or ugly or annoying (like the inability to control scrolling speed in System Preferences) ... but those are minor reasons not to "upgrade".

    This was a tough review to do, and I love Anandtech, but I think you guys skimmed over some very important negatives. I don't know a single person who is not an Apple employee or stock owner who claims to really like Lion ... come to think of it I haven't yet met an employee who really likes it, so it is pretty much stock owners who are saying it is an upgrade-without-quotation-marks. Although a lot of employees do genuine like the full-screen mode.
    Reply
  • tomeg - Wednesday, October 12, 2011 - link

    nardreiko said:
    "I don't know a single person who is not an Apple employee or stock owner who claims to really like Lion ... come to think of it I haven't yet met an employee who really likes it, so it is pretty much stock owners who are saying it is an upgrade-without-quotation-marks. Although a lot of employees do genuine like the full-screen mode."

    tomeg replies:
    I have a circle of nearly 200 fellow Mac users—real, (mostly) unbiased, not-at-all picky or ego-inflated (I'm not suggesting that you are), everyday-if-not-hour-intensive Mac users—and our experience has been 95% positive or enthusiastic. Some are disappointed with the loss of or change to this or that, as am I, and we have to adjust, go As The Mac OS Turns, but not one isn't glad they upgraded. Any OS must continue to be evolutionary or die. Some things go, others stay, but the overall progress is forward. I will take Lion over Windows 7 hands down this or any day. Windows has its features and (of course) fans but I'm not buying, now or ever, unless something goes massively wrong with current OS development.
    Reply
  • bjoff - Sunday, September 04, 2011 - link

    Thanks for an enlightening test! One thing I wish you had tested was the time to wake from sleep. On my macbook air (with very similar specs to your setup), it seems that waking from sleep takes a couple of seconds more with FileVault enabled. This is pretty significant when you are used to the very quick waking of Apple products... Reply
  • raygos - Wednesday, September 21, 2011 - link

    The reviewer complains that Resume can be annoying for the likes of him/her when a clean slate is desired. He/she writes: "I found myself pressing command-W a bunch of times to close windows before I'd press command-Q to quit the program." There is, of course, the shortcut command-option-W to close all open windows in the active application. For mousers, press option while clicking the red "close window" button does the same thing. Gotta save those clicks! Reply
  • dtalari - Friday, October 28, 2011 - link

    I am a work-study at a college and we recently bought a bunch of IMACS to make an IMAC Labs for all the students. We also have a few for the staff. We had Snow Leopard installed initially and we were able to connect perfectly fine to all of the servers within our network,however since our implementation of lion the servers don't show up under the shared tab in the finder automatically like before. The computers on the network show up but not the servers. Anyone have any ideas as to why? I figured it has something to do with samba not being implemented as it was in Snow Leopard? Is there any easy way to change a setting? Or do I have to manually add each server to each computer?
    Thanks
    Reply

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