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Virtualized Linux Faster Than Native?
^switch writes "Aussies at NICTA have developed a para-virtualized Linux called Wombat that they claim outperforms native Linux. From the article: 'The L4 Microkernel works with its own open source operating system Iguana, which is specifically designed as a base for use in embedded systems.'" Specific performance results are also available from the NICTA website.
Warning
Running a virtual Iguana OS from within a virtualised Linux environment is dangerous.
ETROS and NICTA will not be held responsible for any resulting time paradoxes.
hmmmm
liqbase
I can Linus already gearing up to defend his position that microkernels are crap.
However, I thought the purpose of a microkernel was stability, not performance.
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Ignore the second link. The actual performance results are here.
Just how fast would a virtualized Linux instance running inside of a virtualized Linux instance running on hardware be?
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The summary is misleading a bit - it's only faster on ARM v4 or v5 processors.
From TFA:
Wombat, NICTA's architecture-independent para-virtualised Linux for L4-embedded, can be faster than native Linux on the same hardware. Specifically on popular ARM v4 or v5 processors, such as ARM9 cores or the XScale, Wombat benefits from the fast address-space switch (FASS) technology implemented in L4-embedded, while this is not supported in native Linux distributions.
They sacrificed portability by performing some TLB caching hacks. It's a good idea but comparing it to Linux as a whole is a bad idea as Linux runs on more than the ARM they're testing on. If you look at all of the results most are comparable and exec/fork favour Linux.
Tom
Someday, I'll have a real sig.
It is possible. First you have drive access. Normally the data is buffered in memory then is paged out to the drive when the OS sees fit. When it is on the memory it can be accessed faster. So now you are virtualizing the hardware so when the OS says write to the Hard Drive it goes to the Host OS who then buffers it in memory and writes to the drive when it seems fit, so the files are buffered in memory for twice as long, allowing twice the time that it can access the faster data. Usually that is the largest slowdown on the system is drive access, also because when the host OS is writing to the drive the Virtualized Linux kernel is free to do what it wants. I am sure if the application requires a lot of interrupt calls or a lot of displaying to the screen it will slowdown (Unless the virtualized video drivers are much more optimized then the normal ones)
So it is possible, just as long as you have a system powerful enough to run both OSs well and with a lot of RAM.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Could it be because linux for ARM is not that well optimised . I can't imagine such massive performance gains otherwise , bar a massive bug in the kernel.
Fast Address-Space Switching for ARM Linux Kernels
The Fast Address-Space Switching (FASS) project aims to utilise some of the features of the Memory Management Unit in the ARM architecture to improve the performance of context switches under the L4 kernel and ARM Linux.
The only things certain in war are Propaganda and Death. You can never be sure which is which though
I'm not sure if you realize the market penetration of ARM-based processors. They're basically everywhere. One popular use is in routers. Many printers also have ARM chips. They're also very widely used in cell phones and other mobile technology.
It benefits us all of more performance can be extracted from such chips, just because they're so widely used. Being able to get a greater degree of performance out of a device already in use can lead to lower-cost systems. To suggest that this is of limited use is naive, just because of how prevalent these processors are.
I think that the whole L4 family smicrokernels hould deserve some more attention from IT professionals.
As far as I know L4 is one of the microkernels with more efforts for development. Along with MinixV3 of course.
Maybe Computers will never be as intelligent as Humans.
For sure they won't ever become so stupid. [VR-1988]
Whenever a free microkernel design comes remotely close to the mindshare of Linux, there may be a basis for discussion.
QNX
'Nuff said.
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NICTA... necktie...
Definitely an n-word.
More
He doesn't thinks microkernels are "crap".
He just wants to build a stable, reliable and fast operative system, like the microkernel guys and like veryone else. The difference is that microkernel guys think that the One Way to achieve that is to compartmentalize everything. Linus however seems to think that the microkernel model makes programming much harder (due to multiple separate address spaces, etc) and that a monolithic kernel makes programming so much easier, than in return you get a stabler, faster kernel.
(Emphasis in the original text). This is one of my pet peeves, since I think it's so sloppy use of maths. How can something be "thirty times less?" So, if it takes one second in Linux, it takes them
main(O){10<putchar(4^--O?77-(15&5128 >>4*O):10)&&main(2+O);}
I've been researching more and more into NICTA's microkernel and virtualization (for my L4::BSD idea) and one thing that is important to understand is that NICTA's development is mainly on ARM, the Kenge toolset, as well as the Iguana OS are both much further along on ARM as opposed to i386
;)
Considering the work that NICTA does with companies that produce embedded hardware like Qualcomm, this isn't surprising, but don't go crazy about this.
Linux development is much more fine tuned on x86, and Kenge/Iguana development is much more fine tuned on ARM; no need to start holy wars here
That said, nice work benno, chuck, and gernot (and whomever else I'm forgetting)
Error 407 - No creative sig found
Comment removed based on user account deletion
If one were to use 33 levels of virtualization on the ARM processor, the efficiency is so great that power may be removed and the system runs on its own efficiency. Yeah! We don't need oil anymore.
Even better than the real thing....
I hate to point this out, but if mindshare is the criterion then Windows wins. Considering that the average person is almost always wrong, I tend to think that mindshare is a warning flag, not a recommendation.
Yeah but...imagine a Beowulf cluster of them!
Implement a VFS, the full networking stack as microkernel subsystems and came back to tell me how many different IPC calls you have in your hands
^switch writes "Aussies at NICTA have developed a para-virtualized Linux called Wombat that they claim outperforms native Linux.
So if a para-virtualised microkernel runs a para-virtualised microkernel running Linux, then there should be an even greater speedup?
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So, what are they trying to show? "Because we've implemented support for a certain MMU feature and native Linux hasn't, we've demonstrated that virtualizing Linux on L4 is a good idea"? Doesn't sound perfectly logical to me. Apples and oranges come to mind.
--
I do not like the men on this space ship!> They had a full operating system, GUI, modem drivers, and web browser, that all fit nicely on a floppy. You can't do that without very well written code.
Not quite sure that follows. After all, you can do that* with DOS and I don't believe anyone would claim that it's well written code.
* Well, more or less. You can fit that wacky Caldera browser, Arachne, (beware the 'orrible MIDI music) and some rudimentary network tools (SSH, VNC and ping) on a floppy. Arguably that's not a "full operating system", but I do think my point size != quality still stands.
James
Free (as in soda pop)
'Nuff said.
Javascript + Nintendo DSi = DSiCade
I for one welcome our new Fast Address-Space Switching overlords!
Last time I read Linus talking about microkernels, it was a lot more nuanced than "Microkernels are crap". It was more along the lines that microkernel architectures end up with greater complexity and more comunication overhead at higher levels. It certainly leaves open the possiblity that a particular microkernel could be fast at a particular set of operations.
What's interesting about a what we're apparently talking here is a virtualized linux running on top of a microkernel. I'm reasonably certain that they didn't do a complete reengineering of Linux as a microkernel, they just got it to run on top of a microkernel. So, we're still talking about a monolithic kernel with all kinds of tight coupling, but the virutalized hardware can make certain hardware related tasks faster. In particular they talk about context switches being much faster; since the microkernel is specifically designed for single architecture (ARM), it may not be so surprising that they can take better advantage of certain architectural features.
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Please.
A low slashdot id just means you've been heaping shit on the pile longer than anyone else.