Test Day:2009-09-17 Virtualization KSM
|Thursday Sep 17, 2009||All day||#fedora-test-day (webchat)|
What to test?
If you come to this page after the test day is completed, your testing is still valuable, and you can use the information on this page to test KSM and provide feedback.
Justin Forbes is your host for today.
The following people have also agreed to be available for testing, workarounds, bug fixes, and general discussion:
- add your name here
What's needed to test
- A fully updated Fedora 12 Rawhide machine. See instructions on the main test day page.
- At least one guest image installed before the test day (suggested reading - Virtualization_Quick_Start)
Things to test, roughly in dependency order:
|Installation|| Install F12 on the host, then install multiple virtual machines of the same type. To speed up this process you can install a single virtual machine and use virt-clone to make additional virtual machines for testing. For KSM to properly function you need to ensure you have the latest qemu installed (version should be 0.10.92-4.fc12).
If there are any installation errors or dependency problems, these are serious bugs and should be reported.
|Start up||First start the ksm service. Start up just one of the virtual machines. Take a look at /sys/kernel/mm/ksm/pages_shared. There should be a non zero value here, the actual value is less important, but take note of it. Next start up additional virtual machines and check /sys/kernel/mm/ksm/pages_shared again. The value should increase over a single running guest.|
|ksmtuned||Try shut down all of the virtual machines and start the ksmtuned service. Once the service has started, restart the virtual machines one at a time. How does the ksm performance compare to ksm without ksmtuned? If there is a drastic difference for the better or the worse, please mention it in IRC.|
Thanks for your contribution to making Fedora better and less buggy!
Issues that were identified
- after turn off of all (two) KVM guests virt-manager frozen, known bug
- ksm and ksmtuned are quite the same wrt shared pages and memory consumption... tested on Rawhide host with two Rawhide guests (one cloned from the other)
- KSM - 1620 MB / ~20.000 shared pages
- KSMtuned - 1600 / ~15.000 shared pages (surprisingly)
- it is 2 GB system and some 500 MB of operating memory was still free after running two guests, shame I didn't know that the page merging is more often when the memory gets tighter...