Archived/Xen 4.3 RC4 test instructions
What needs to be tested
General things:
- Making sure that Xen 4.3 compiles and installs properly on different software configurations; particularly on distros
- Making sure that Xen 4.3, along with appropriately up-to-date kernels, work on different hardware.
Chenges/fixes from RC3
- x86/vtsc fix
- x86/xsave fixes
- VPMU workaround enabling
- fixes related to IOMMU operations and IRQ handling in x86
- xl cd-insert fix
Specific features:
- Automatic NUMA placement of guests.
- Upstream Qemu for HVM domains
- Openvswitch integration: see Setting Up OpenvSwitch Networking for more information
- Xen on ARM
- Windows 2003 support
- others?
Older Xen Features where we are not sure how much test coverage these got (andf are thuis marked experimentral):
- Credit 2 Scheduler
- Nested Virtualization
For more ideas about what to test, please see Testing Xen.
Installing
Getting RC4
- xen: Pull from the main repo, and update to tag
4.3.0-rc4
:
git clone -b 4.3.0-rc4 git://xenbits.xen.org/xen.git
- tarball: Xen 4.3.0 RC4 Tarball (and signature)
Building
Instructions are available for building Xen on Linux and NetBSD.
Test instructions
General
- Remove any old versions of Xen toolstack and userspace binaries (including
qemu
). - Download and install the most recent Xen 4.3 RC, as described above. Make sure to check the
README
for changes in required development libraries and procedures. Some particular things to note:- In Xen 4.3 the default installation path has changed from
/usr
to/usr/local
. Take extra care when removing any old versions to allow for this.
- In Xen 4.3 the default installation path has changed from
Once you have Xen 4.3 RC installed check that you can install a guest etc and use it in the ways which you normally would, i.e. that your existing guest configurations, scripts etc still work.
In particular if you are still using the (deprecated) xm/XEND toolstack please do try your normal use cases with the XL toolstack. The XL page has some information on the differences between XEND and XL. As do the instructions from the Xen 4.2 test day.
Specific Test Instructions
Automatic NUMA placement of guests
In Xen 4.3 you will find both automatic NUMA placement of guests at creation time (which was already in Xen 4.2), and NUMA aware scheduling (for the Credit Scheduler). The former is about allocating the memory of a VM from the least possible number of NUMA node, the latter is about scheduling the VM's vCPUs on those NUME nodes without any need of statically pinning them there.
A NUMA host is required to test these features. numactl --hardware , on bare metal, and/or xl info -n , on Dom0, can tell you if you have one
|
NUMA placement
- create a config file for a VM without any
cpus = "..."
option in it - create the VM with
xl -vvv create vm1.cfg
and check the output for something like the below:
libxl: debug: libxl_numa.c:475:libxl__get_numa_candidate: New best NUMA placement candidate found: nr_nodes=1, nr_cpus=8, nr_vcpus=18, free_memkb=1060 libxl: detail: libxl_dom.c:195:numa_place_domain: NUMA placement candidate with 1 nodes, 8 cpus and 1060 KB free selected
- check that the memory has actually been allocated on (in the case above) just one node by running
xl debug-key u | xl dmesg | tail
(yes, a more easy and convenient method for figuring this out is planned!):
# xl debug-keys u | xl dmesg | tail (XEN) CPU13 -> NODE1 (XEN) CPU14 -> NODE1 (XEN) CPU15 -> NODE1 (XEN) Memory location of each domain: (XEN) Domain 0 (total: 2777077): (XEN) Node 0: 1271001 (XEN) Node 1: 1506076 (XEN) Domain 2 (total: 245760): (XEN) Node 0: 245760 (XEN) Node 1: 0
- use
xl info -n
andxl vcpu-list
to verify that the NUMA node affinity is what is being used (instead of the vCPU affinity, as it was for Xen 4.2):
# xl list -n Name ID Mem VCPUs State Time(s) NODE Affinity Domain-0 0 10847 16 r----- 106.3 any node vm1 2 960 2 -b---- 10.0 0 # xl vcpu-list vm1 Name ID VCPU CPU State Time(s) CPU Affinity vm1 2 0 5 -b- 5.3 any cpu vm1 2 1 0 -b- 4.8 any cpu
NUMA aware scheduling
The idea here is trying to make sure that the vCPUs of a VM run as much as possible on the pCPUs of the NODE(s) the VM has node affinity with. This is something non trivial to analyze and verify. Some hints and examples on how that can be done are available in this blog post. An easy, but unreliable way to at least have an idea if something is going wrong follows:
- create a VM, as above, without specifying any pinning in the config file:
# xl create /etc/xen/vm1.cfg Parsing config from /etc/xen/vm1.cfg Daemon running with PID 4632 # ping 192.168.0.221 PING 192.168.0.221 (192.168.0.221) 56(84) bytes of data. 64 bytes from 192.168.0.221: icmp_req=1 ttl=64 time=0.620 ms ...
- make sure the vCPUs are busy:
$ ssh root@192.168.0.221 "yes &> /dev/null &" $ ssh root@192.168.0.221 "yes &> /dev/null &" $ ssh root@192.168.0.221 "yes &> /dev/null &" $ ssh root@192.168.0.221 "yes &> /dev/null &" $ ssh root@192.168.0.221 "ps aux|grep yes" root 1749 51.0 0.0 5596 608 ? R 11:11 1:43 yes root 1753 49.7 0.0 5596 608 ? R 11:11 1:38 yes root 1757 49.4 0.0 5596 608 ? R 11:11 1:37 yes root 1761 49.4 0.0 5596 608 ? R 11:11 1:36 yes
- use
xl vcpu-list vm1
many times, and ideally under different load conditions (e.g., other busy VMs), and verify that the vCPUs are actually scheduled on the pCPUs (CPU
column) of the proper NUMA node:
# xl vcpu-list vm1 Name ID VCPU CPU State Time(s) CPU Affinity vm1 3 0 1 r-- 444.9 any cpu vm1 3 1 4 r-- 419.0 any cpu
Stress testing
NUMA node affinity (on a per-domain basis, for now) and vCPU pinning (on a per-vCPU basis) can coexist. Semantic is that pinning should always prevail on NODE affinity. A sensible way to verify it is creating a VM with a NODE affinity (as explained above) and change on-line the vCPU pinning of its vCPUs, checking, again, with xl list -n
and xl vcpu-list
that the results is what one would have expected.
Upstream Qemu for HVM domains
In Xen 4.3 we have switched to using upstream qemu (which xl calls "qemu-xen") to provide the device model when running HVM guests instead of the older Xen fork of Qemu (which xl calls "qemu-xen-traditional). Interesting things to test in this context:
- Does the new device model support the guest OSes which you use, can you install as you would have with the old device model?
- Do features behave as expected, e.g. migration, VNC console.
- Do previously installed HVM guests, installed with qemu-xen-traditional, work when switched to qemu-xen?
- It is expected that some guest types will not like the change in hardware which this entails. In this case is setting
device_model_version="qemu-xen-traditional"
in the guest configuration sufficient to make the guest OS happy again? - If the guest doesn't seem to mind this change then this is useful information, please report it to us.
- Note: The new device model does not yet support stubdomains and so the default is unchanged if you request stubdomains.
- It is expected that some guest types will not like the change in hardware which this entails. In this case is setting
- Does the old device model still work if you set
device_model_version="qemu-xen-traditional"
in the guest configuration? - Do new features enabled by the new device model, such as SPICE graphics, work?
Openvswitch integration
Xen 4.3 adds support for Open vSwitch based networking in addition to the existing bridge and routed networking schemes.
In order to test this you will need to setup a host with openvswitch support. Information on this is available at http://openvswitch.org/support/. In summary you need to:
- Install a domain 0 kernel with CONFIG_OPENVSWITCH enabled (any recent PVOPS kernel should have this option).
- Install the Open vSwitch userspace, see http://openvswitch.org/download/.
- Configure the host networking to use Open vSwitch instead of bridge.
e.g. to create a switch (which we will call xenbr0 to simplify the transition) and add eth0 as a physical port:
# ovs-vsctl add-br xenbr0 # ovs-vsctl add-port xenbr0 eth0
These appear to be persistent reboot, so only need to be done once. Now you should arrange to add an IP address to xenbr0, e.g. under Debian create an entry in /etc/network/interfaces
:
auto xenbr0 iface xenbr0 inet dhcp
(remember to remove/comment any bridge related items like bridge_ports eth0
)
Once the host is configured you need to configure the system to use vswitch for guests. You can do this by editing /etc/xen/xl.conf and setting:
vifscript=vif-openvswitch
Now you can try starting your guests and performing the usual operations on them (e.g. reboot, migrate etc) and verify that the network is accessible to the guest.
Xen on ARM
TBD
Reporting Bugs (& Issues)
- Report any bugs / missing functionality / unexpected results.
- Please put [TestDay] into the subject line
- Also make sure you specify the RC number you are using
- Make sure to follow the guidelines on Reporting Bugs against Xen.
Reporting success
We would love it if you could report successes by e-mailing xen-devel@lists.xen.org
, preferably including:
- Hardware: Please at least include the processor manufacturer (Intel/AMD). Other helpful information might include specific processor models, amount of memory, number of cores, and so on
- Software: If you're using a distro, the distro name and version would be the most helpful. Other helpful information might include the kernel that you're running, or other virtualization-related software you're using (e.g., libvirt, xen-tools, drbd, &c).
- Guest operating systems: If running a Linux version, please specify whether you ran it in PV or HVM mode.
- Functionality tested: High-level would include toolstacks, and major functionality (e.g., suspend/resume, migration, pass-through, stubdomains, &c)
The following template might be helpful: should you use Xen 4.3.0-RC1 for testing, please make sure you state that information!
Subject: [TESTDAY] Test report * Hardware: * Software: * Guest operating systems: * Functionality tested: * Comments:
For example:
Subject: [TESTDAY] Test report * Hardware: Dell 390's (Intel, dual-core) x15 HP (AMD, quad-core) x5 * Software: Ubuntu 10.10,11.10 Fedora 17 * Guest operating systems: Windows 8 Ubuntu 12.10,11.10 (HVM) Fedora 17 (PV) * Functionality tested: xl suspend/resume pygrub * Comments: Window 8 booting seemed a little slower than normal. Other than that, great work!