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

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Subject: [Xen-devel] Fwd: HELP required with some ideas
From: grapgroup grapgroup <we.are.grap@xxxxxxxxx>
Date: Sun, 29 Aug 2010 18:17:06 +0530
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 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 :

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.

  Rohan Malpani
  Ammar Ekbote
  Paresh Nakhe
  Gaurav Jain

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.

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.

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    

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