ASUS Eee PC / Intel Atom: Disk Encryption Performance

In both the synthetic and real-world tests, fully encrypting the solid-state storage on the ASUS Eee PC 901 had resulted in a performance loss. In some tests it was more noticeable than others were, but in all of them the performance had dropped. When sequentially creating files with Bonnie++, for this Intel Atom Netbook with encrypted media had dropped from 6,625 to 5,264 operations per second. The random read performance was impacted even more severely dropping from 28,820 to 18,788 operations per second. With the Flexible IO Tester it had taken nearly 17 minutes to run Intel's IOMeter File Server Access Pattern while when the drive was unencrypted it took about 12 minutes. In the example network job generated by the Flexible IO Tester, however, the difference was negligible.

With the ImageMagick compilation time being monitored as one of our real-world tests, it took about 3.6% more time when running on an encrypted file-system. Like the example network job with the Flexible IO Tester, the Tandem XML read and write performance was roughly the same in both situations. One the biggest drops in performance of an encrypted file-system came when testing out SQLite, which is the open-source relational database system used by Firefox, Skype, and other applications. Here the encrypted system had caused a 45% drop in performance when performing just 2,500 SQL insertions.

While the entire file-system was already encrypted, we had also tested GnuPG to see how long it would take to encrypt a 1GB file. Here the performance difference was significant and it amounted to running 23% slower. Last but not least, the Sunflow ray-tracing performance was about the same in both test runs.

When testing out the dm-crypt Ubuntu Linux performance on a dual-core AMD processor with a Serial ATA hard drive earlier this year, the real-world performance wasn't impacted greatly. However, encrypting data on mobile devices using Intel Atom hardware does have its consequence. In some tests, the change in performance would not be noticeable to the end-user, but in other tests, the performance drop was as much as 45% slower. Even with the drop in performance though, we still would take the route of fully encrypting the non-volatile memory to protect information in the event the netbook or notebook computer is lost or stolen. For those looking at a route that will not impact the system performance as much, a user can optionally encrypt just a single directory that contains sensitive information or encrypt just their /home/ partition.