Re: [Xen-devel] Fwd: HELP required with some ideas

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Sun, Aug 29, 2010 at 06:17:06PM +0530, grapgroup grapgroup wrote:
>    Hi,
>     We are a group of four students studying in an undergraduate college.
>     We are new to XEN and we would like to contribute to the development of
>    XEN through our college final year project.
>     We have gone through a few research papers and have shortlisted a few
>    ideas out of which we are going to finalize the project.
>     As we are beginners we would be very grateful if you could guide us in
>    any of the following ways :
> 

Hello!

Could you send the links the papers you mention?
Some comments below..

>    1)  telling us if the idea is already implemented in
>    XEN.                                                       OR
>    2)  if the idea is implemented then suggesting any modifications which can
>    be done in it.       OR
>    3)  telling the feasibility of the idea.
> 
>    We would be very thankful if you could guide us in any way.
>    We would also like to think on any ideas suggested by you.
> 
>    Regards,
>      Rohan Malpani
>      Ammar Ekbote
>      Paresh Nakhe
>      Gaurav Jain
> 
>    *******************************IDEAS*****************************
>    1) Disk I/O scheduling on virtual machines
> 
>        Scheduling algorithms for native OS are designed keeping in mind the
>    latency characteristics of the disk. In virtual environment, a
>    VM will have a virtual disk which is physical space on the physical disk.
>    Therefore, the same algorithms do not work well on virtual
>    machines. There is a need of new scheduling algorithms for VMs which will
>    take into account the type of workload and perform schduling in
>    such a way so as to increase the preformance. The paper we referred
>    suggested using two level scheduling, one at the VM level and other at
>    the hypervisor level.
> 

Have you guys looked at projects like dm-ioband ?


>    2) Network Interface Virtualization
> 
>        There is a particular mechanism in XEN called 'Page grant mechanism'
>    to achieve network interface virtualization. In this
>    mechanism there is considerable s/w overhead as for each I/O, access to
>    certain guest pages(I/O buffer) is granted to driver domain and is
>    immediately revoked as soon as the i/o is complete. Current mechanism is
>    said to be giving  a performance 2.9 Gb/s on 10 Gb/s line. The paper
>    we referred suggested a mechanism where this s/w overhead can be reduced
>    to a great extent.
>    First  is implementation of multi-queue NIC support for the driver domain
>    model in Xen and other is grant reuse mechanism based on
>    software I/O address translation table. In this,once the access to guest
>    pages is granted it is reused for multiple i/o transactions.
> 

Some of this stuff is done in the xen 'netchannel2' development.

I think there are multiple presentations about possible xen network
improvements available from XenSummit slides.

>    3) Asymmetry aware hypervisor
> 
>        Experiments show that asymmetric multi-core processors are more
>    efficient than the SMP. Idea is to deliver better performance
>    per watt and per area. The paper suggests that each VM running on the
>    hypervisor has some number of fast vCPUs and some number of slow
>    vCPUs. Each task is identified for its type and accordingly sent to fast
>    or slow vCPU. CPU intensive applications are scheduled on fast
>    vCPUs and memory intensive applications are scheduled on slow vCPUs. These
>    vCPUs are mapped to the corresponding type of physical
>    core. Hypervisor needs to modified to become asymmetry aware. The goals of
>    such a hypervisor are
> 
>    1.fair sharing of fast cores among all vCPUs in the system;
>    2.support for "asymmetry aware" guests;
>    3.a mechanism for controlling priority of VMs in using fast cores;
>    4.a mechanism ensuring that fast cores never go idle before slow cores

Hmm.. do you mean NUMA aware hypervisor/VMs, or something else?

-- Pasi


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