[clug] Ubuntu encrypted file systems

[Daniel Pittman]

Jim Croft <jim.croft at gmail.com> writes:

> is there a detectable/measurable performance hit with the encryption?

Yes, but not often that you will notice.  On a Core2 CPU, negligible: high
volume writes can stall the system[1], but that takes hundreds of megabytes
of data queued.

On an Atom CPU things probably look a little different: when I benchmarked one
the performance difference was closing in on an order of magnitude, so it
might hurt.

The real question, I think, is how often you need to touch disk: with 4GB of
RAM encryption for reads is going to hurt a lot less than with 1GB, since an
awful lot more can be cached.


At the end of the day, though, it depends a lot on your personal use patterns
for the machine.

        Daniel

Footnotes: 
[1]  This is, I think, a bug, in that the encryption code doesn't relinquish
     the CPU effectively, as it has a couple of times managed to trigger an
     NMI based "task lockup" warning.

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