using
xenbus_read
xenbus_scanf.
and putting a watch on the path .
we can read the xenstore values at kernel.

Xen Virtualization(cont.)

Shared info pages
-provides information to the kernel at boot up
-functionality analogous to BIOS
-also used during runtime to get the overall state of the system.
Also going through grant table concept which allows the memory pages to be shared or transferred between domains.
Also trying out tcp client server implementation for passing config info.

Xen Virtualization(cont)

Studied about xenstore and xenbus for inter-domain comm.
xenstore, analogous to proc fs, used to store info by 1 domain which can be accessed by info from another domain
xenbus is an abstraction of actual bus which is used to communicate config and staus info between domains
xenstore-write , xenstore-read commands are available to access xenstore directly
probe function is triggered for a driver when a value corresponding to the device is written on to the xenstore.
Also cont. the tcp server ,client thing

Xen Virtualization (cont)

Netback started a module
trying a tcp server to start up in init_module
so that a external tcp client can communicate with it to pass
config info..

Also studied the netback - netfront mechanism
evt-channel mechanism.

Xen Virtualization(cont)

- checking out hyper call mechanism to find out where exactly the dom0 control is passed to hypervisor
- the working of event channel
- the driver part is loaded as a module so checking out ways to pass the config parameters when the module loads.

Xen Virtual;ization (cont)

Code study of xm (command line tool for xen)
code study of xend (python daemon for parsing and processing xm commands)
used pdb for the debugging purpose.
code studyof dom0 part where xend sends config info.
using printk for understanding the code flow.
Algo
--------
understanding the flowchat.
answered qns like
1. who assigns sequence no for packets
2.sum of credits is constant or not after redistribution

Xen Virtualization(cont)

Attended stage 3 ppts.
Doing scheduler validation experiments.
Going to netback.c code.

Xen Virtualization(cont.)

Experiments for need of QoS
- finding parameters for Bench mark load.
- pin vcpus to pcpu
- find utilization
Review of report Saransh and Piyush.

List of xm commands
http://www.centos.org/docs/5/html/Virtualization-en-US/virt-task-xm-managing.html

A discussion on VCPUs and CPU affinity
http://markmail.org/message/mlbmog4xdvqfcki3?q=how+to+get+info+about+the+cpus+for+using+xm+vcpu-pin+command&page=1&refer=63bw5tbz6mhwzxzx

Using vcpu-pin command
http://book.xen.prgmr.com/mediawiki/index.php/Scheduling

started experiments.
Review of reports.

Xen Virtualization(cont.)

Applied event channel patch on the kernel.
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/7fe1c6d02a2b

Folder to be modified $XEN_HOME/linux-2.6-xen-sparse
source path - drivers/xen/core/evtchn.c

Remove the lines label -- and add those labeled ++
compile xen( make world , make install)

Also reading report , credit scheduler algorithm and experiments

Xen Virtualization (cont.)

Xen networking -
http://wiki.xensource.com/xenwiki/XenNetworking
http://lists.xensource.com/archives/html/xen-users/2006-02/msg00030.html
http://www.debian-administration.org/articles/360

cpu credit scheduler - setting cpu weights and caps.
xm sched-credit -d <domain>

Tried basic commands with xen networking and setting weights.

Xen Virtualization (cont.)

Installed Xen from source.
Installation proc -
Installed 2 dapper guest domains .
Installation proc -http://www.debian-administration.org/article/A_brief_introduction_to_xen-tools
Tried out basic xm commands.
[ Next - read Xen networking, how to set cpu weights , start exps]

Xen Virtualization

1. Reading previous reports and installing Xen.
2. ubuntu 7.04 Xen 3.1.3 source xorg-x11-dev pkg not found
3. gcc -B option not found.. trying binutils-dev. apt-get and wget config probelms