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Re: [Xen-devel] Introduction to VirtIO on Xen project

To: Wei Liu <liuw@xxxxxxxxx>
Subject: Re: [Xen-devel] Introduction to VirtIO on Xen project
From: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Date: Wed, 27 Apr 2011 14:29:02 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
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Welcome!  This looks like a good project -- looking forward to seeing it done!


On Wed, Apr 27, 2011 at 3:53 AM, Wei Liu <liuw@xxxxxxxxx> wrote:
> Hi, all.
> I'm Wei Liu, a graduate student from Wuhan University, Hubei, China.
> I'm accepted to GSoC 2011 for Xen and responsible for the project
> VirtIO on Xen. It's my honor to get accepted and involved in this
> wonderful community. I've been doing Xen development for my lab since
> late 2009.
> As you all know, VirtIO is a generic paravirtualized mainly used in
> KVM now. But it should not be too hard to port VirtIO to Xen. When
> done, Xen will have access to Linux kernel's VirtIO interfaces and
> developers will have an alternative way to deliver PV drivers besides
> from the original ring buffer flavor. This project requires: Modify
> upstream QEMU, replace KVM-specific interface with generic QEMU
> function; Modify Xen / Xentools to support VirtIO; Modify Linux
> kernel's VirtIO interfaces.
> We must take two usage scenarios into consideration:
> 1. PV-on-HVM;
> 2. Normal PV.
> These two scenarios require working on different set of functions:
> 1. XenBus vs VirtualPCI, it's about how to create a channel;
> 2. PV vs HVM, it's about how events are handled.
> Most of the code in VirtIO will be left as-it-is. But the notification
> mechanism should be replaced with Xen's event channel. This applies to
> QEMU's porting as well.
> In the PV on HVM case, QEMU needs to use event channel to get / send
> notification and foreign mapping / grant table functions in libxc
> /libxl to map memory pages. Virtual PCI bus will be used to establish
> a channel between Dom0 and DomU. In some sense, it makes no
> differences on the Linux kernel side.
> In the normal PV case, QEMU needs to use event channel to get / send
> notification, and foreign mapping functions in libxc / libxl to map
> memory pages. XenBus / Xenstore will be used to establish a channel
> between Dom0 and DomU. Linux VirtIO driver should use Xen's event
> channel as kick / notify function.
> When the porting is finished, I will carry on some performance tests
> with standardized tools such as ioperf, netperf and kernbench.
> Testsuites will be run on five different configurations:
> 1. Native Linux
> 2. Xen with PV-on-HVM VirtIO support
> 3. Xen with normal PV VirtIO support
> 4. Xen with original PV driver support
> 5. KVM with VirtIO support
> A short report will be written based on the results.
> This is a brief introduction to the project. Any comments are welcomed.
> --
> Best regards
> Wei Liu
> Twitter: @iliuw
> Site: http://liuw.name
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