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Article:		An Unencrypted Look at FileVault
Subject:		FileVault performance tax
Date:		2003-12-21 15:03:51
From:		tychay
Response to: FileVault performance tax
It's the other way around. NT and Darwin have a microkernel and Linux has a monolithic. Not too sure if it is a big issue anymore since many of the advantages of a ukernel have been incorporated in Linux, very few things take advantage of the inherent advantages of a ukernel ("Classic" old Windows compatibility), and the slowdown of a ukernel vs. a monolithic gets marginalized as applications get more complex. (Certainly not an "order of magnitude" like the original flamebait claims.) Honestly, if Darwin were so slow, then why is the #3 fastest supercomputer using it? Certainly there are Linux drivers for the G5 now--heck, 64-bit support is now standard in kernel 2.6. BTW, Linux is far good for more than just a server. It makes the core of many excellent operating system distributions. It is an excellent and rapidly improving embeddable operating system (in fact, I think it will overtake WindowsCE at the rate its going). It now has even hooks for the beginnings of a serious real-time operating system.

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FileVault performance tax
2003-12-26 21:19:45 anonymous2 [View]

I can't comment on NT but the original CMU and OSF Mach are ukernels, Apple xnu is not in the true sense. The FreeBSD "server" is not a real Mach server but bolts directly onto Apple's own variant of Mach so there is really no major slowdown there. Nevertheless, there is some overhead with making BSD system calls. Depending on what you want to do, task_self() might be more appropriate than getpid(). I'm also not sure how you actually timed the system calls. FYI, there are no release-quality kernels that will leave you with a working G5 Linux system, there is no accelerated OpenGL on NVIDIA cards and ppc64 64-bit Linux is not in any sense standard in kernel 2.6. Linux probably makes a poor choice if you want to do anything serious on your (Apple) ppc. As for the TLB overhead etc. pick up a good book on computer architecture and the ppc user manuals: the code for managing the TLB is very standard (read: same) across any operating system that will run on the ppc.