On Tue, Mar 13, 2012 at 2:06 PM, Florian Philipp <li...@binarywings.net> wrote: > Am 13.03.2012 18:45, schrieb Frank Steinmetzger: >> On Tue, Mar 13, 2012 at 05:11:47PM +0100, Florian Philipp wrote: >> >>>> Since I am planning to encrypt only home/ under LVM control, what kind >>>> of overhead should I expect? >>> >>> What do you mean with overhead? CPU utilization? In that case the >>> overhead is minimal, especially when you run a 64-bit kernel with the >>> optimized AES kernel module. >> >> Speaking of that... >> I always wondered what the exact difference was between AES and AES i586. I >> can gather myself that it's about optimisation for a specific architecture. >> But which one would be best for my i686 Core 2 Duo? > > From what I can see in the kernel sources, there is a generic AES > implementation using nothing but portable C code and then there is > "aes-i586" assembler code with "aes_glue" C code.
> So I assume the i586 > version is better for you --- unless GCC suddenly got a lot better at > optimizing code. Since when, exactly? GCC isn't the best compiler at optimization, but I fully expect current versions to produce better code for x86-64 than hand-tuned i586. Wider registers, more registers, crypto acceleration instructions and SIMD instructions are all very nice to have. I don't know the specifics of AES, though, or what kind of crypto algorithm it is, so it's entirely possible that one can't effectively parallelize it except in some relatively unique circumstances. -- :wq
