Talk:COMP 3000 Essay 2 2010 Question 9

Group members

• Munther Hussain
• Jonathon Slonosky
• Michael Bingham
• Chris Sullivan
• Pawel Raubic

Group work

• Background concepts: Munther Hussain
• Research problem:
• Contribution:
• Critique:

General discussion

Hey there, this is Munther. The prof said that we should be contacting each other to see whos still on board for the course. So please if you read this, add your name to the list of members above. You can my find my contact info in my profile page by clicking my signature. We shall talk about the details and how we will approach this in the next few days --Hesperus 16:41, 12 November 2010 (UTC)

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Checked in -- JSlonosky

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Pawel has already contacted us so he still in for the course, that makes 3 of us. The other three members, please drop in and add your name. We need to confirm the members today by 1:00 pm. --Hesperus 12:18, 15 November 2010 (UTC)

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Checked in --Mbingham 15:08, 15 November 2010 (UTC)

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Checked in --Smcilroy 17:03, 15 November 2010 (UTC)

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To the person above me (Smcilroy): I can see that you're assigned to group 7 and not this one. So did the prof move you to this group or something ? We haven't confirmed or emailed the prof yet, I will wait until 1:00 pm. --Hesperus 17:22, 15 November 2010 (UTC)

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Alright, so I just emailed the prof the list of members that have checked in so far (the names listed above plus Pawel Raubic), Smcilroy: I still don't know whether you're in this group or not, though I don't see your name listed in the group assignments on the course webpage. To the other members: if you're still interested in doing the course, please drop in here and add your name or even email me, you can find my contact info in my profile page(just click my signature).

Personally speaking, I find the topic of this article (The Turtle Project) to be quite interesting and approachable, in fact we've already been playing with VirtualBox and VMWare and such things, so we should be familiar with some of the concepts the article approaches like nested-virtualization, hypervisors, supervisors, etc, things that we even covered in class and we can in fact test on our machines. I've already started reading the article, hopefully tonight we'll start posting some basic ideas or concepts and talk about the article in general. I will be in tomorrow's tutorial session in the 4th floor in case some of you guys want to get to know one another. --Hesperus 18:43, 15 November 2010 (UTC)

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Yeah, it looks pretty good to me. Unfortunately, I am attending Ozzy Osbourne on the 25th, so I'd like it if we could get ourselves organized early so I can get my part done and not letting it fall on you guys. Not that I would let that happen --JSlonosky 02:51, 16 November 2010 (UTC)

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Why waste your money on that old man ? I'd love to see Halford though, I'm sure he'll do some classic Priest material, haven't checked the new record yet, but the cover looks awful, definitely the worst and most ridiculous cover of the year. Anyways, enough music talk. I think we should get it done at least on 24th, we should leave the last day to do the editing and stuff. I removed Smcilroy from the members list, I think he checked in here by mistake because I can see him in group 7. So far, we're 5, still missing one member. --Hesperus 05:36, 16 November 2010 (UTC)

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Yeah that would be pretty sweet. I figured I might as well see him when I can; Since he is going to be dead soon. How is he not already? Alright well, the other member should show up soon, or I'd guess that we are a group of 5. --JSlonosky 16:37, 16 November 2010 (UTC)

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Hey dudes. I think we need to get going here.. the paper is due in 4 days. I just did the paper intro section (provided the title, authors, research labs, links, etc.). I have read the paper twice so far and will be spending the whole day working on the background concepts and the research problem sections.

I'm still not sure on how we should divide the work and sections among the members, especially regarding the research contribution and critique, I mean those sections should not be based or written from the perspective of one person, we all need to work and discuss those paper concepts together.

If anyone wants to add something, then please add but don't edit or alter the already existing content. Lets try to get as many thoughts/ideas as possible and then we will edit and filter the redundancy later. And lets make sure that we add summary comments to our edits to make it easier to keep track of everything.

Also, we're still missing one member: Shawn Hansen. Its weird because on last Wednesday's lab, the prof told me that he attended the lab and signed his name, so he should still be in the course. --Hesperus 18:07, 21 November 2010 (UTC)

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Yeah man. We really do need to get on this. Not going to ozzy so I got free time now. I am reading it again to refresh my memory of it and will put notes of what I think we can criticize about it and such. What kind of references do you think we will need? Similar papers etc? If you need to a hold of me. Best way is through email. jslonosk@connect.Carleton.ca. And if that is still in our group but doesn't participate, too bad for him--JSlonosky 14:42, 22 November 2010 (UTC)

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The section on the related work has all the things we need to as far as other papers go. Also, I was able to find other research papers that are not mentioned in the paper. I will definitely be adding those paper by tonight. For the time being, I will handle the background concepts. I added a group work section below to keep track of whos doing what. I should get the background concept done hopefully by tonight. If anyone want to help with the other sections that would be great, please add your name to the section you want to handle below.

I added a general paper summary below just to illustrate the general idea behind each section. If anybody wants to add anything, feel free to do so. --Hesperus 18:55, 22 November 2010 (UTC)

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I remember the prof mentioned the most important part of the paper is the Critique so we gotta focus on that altogether not just one person for sure.--Praubic 19:22, 22 November 2010 (UTC)

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Yeah absloutely, I agree. But first, lets pin down the crucial points. And then we can discuss them collectively. If anyone happens to come across what he thinks is good or bad, then you can add it below to the good/bad points. Maybe the group work idea is bad, but I just thought maybe if we each member focuses on a specific part in the beginning, we can maybe have a better overall idea of what the paper is about. --Hesperus 19:42, 22 November 2010 (UTC)

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Ok, another thing I figured is that the paper doesn't directly hint at why nested virtualization is necessary? I posted a link in references and I'l try to research more into the purpose of nested virtualization.--Praubic 19:45, 22 November 2010 (UTC)

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Actually the paper does talk about that. Look at the first two paragraphs in the introduction section of the paper on page1. But you're right, they don't really elaborate, I think its because its not the purpose or the aim of the paper in the first place. --Hesperus 20:31, 22 November 2010 (UTC)

Paper summary

The idea/goal

The paper provides a solution for Nested-virtualization on x86 based computers. Their approach is software-based, meaning that, they're not really altering the underlying architecture, and this is basically the most interesting thing about the paper, since x86 computers don't support nested-virtualization in terms of hardware. But apparently they were able to do it. In addition, generally, nested virtualization is not supported on x86 systems (the architecture is not designed with that in mind) but for example vista runs XP VM under the covers when running xp programs which shows ability for parallel virtualization on a single hypervisor.

The goal of nested virtualization and multiple host hypervisors comes down to efficiency. Example: Virtualization on servers has been rapidly gaining popularity. The next evolution step is to extend a single level of memory management virtualization support to handle nested virtualization, which is critical for high performance. [1]

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Theory (Section 3.1)

Apparently, theres 2 models to applying nested-virtualization:

• Multiple-level architecture support: where every hypervisor handles every other hypervisor running on top of it. For instance, if L0 (host hypervisor) runs L1. If L1 attempts to run L2, then the trap handling and the work needed to be done to allow L1 to instantiate a new VM is handled by L0. More generally, if L2 attempts to created its own VM, then L1 will handle the trap handling and such.

• Single-level architecture support: This is the model supported by the x86 machines. This model is tied into the concept of "Trap and emulate", where every hypervisor tries to emulate the underlying hardware (the VMX chip in the paper implementation) and presents a fake ground for the hypervisor running on top of it (the guest hypervisor) to operate on, letting it think that he's running on the actual hardware. The idea here is that in order for a guest hypervisor to operate and gain hardware-level privileges, it evokes a fault or a trap, this trap or fault is then handled or caught by the main host hypervisor and then inspected to see if its a legitimate or appropriate command or request, if it is, the host gives privilige to the guest, again having it think that its actually running on the main bare-metal hardware.

In this model, everything must go back to the main host hypervisor. Then the hosy hypervisor forwards the trap and virtualization specification to the above-level involved or responsible. For instance, if L0 runs L1. Then L1 attempts to run L2. Then the command to run L2 goes down to L0 and then L0 forwards this command to L1 again. This is the model we're interested in because this what x86 machines basically follow. Look at figure 1 in the paper for a better understanding of this.

Main contribution

The paper propose two new-developed techniques:

• Multi-dimensional paging (for memory virtualization)
• Multiple-level device management (for I/O virtualization)

Other contributions:

• Micro-optimizations to improve performance.

Critique

The good:

• From what I read so far, the research showed in the paper is probably the first to achieve efficent x86 nested-virtualization without altering the hardware, relying on software-only techniques and mechanisms. They also won the Jay Lepreau best paper award.

The bad:

References

[1] http://www.haifux.org/lectures/225/ - Nested x86 Virtualization - Muli Ben-Yehuda