On Tue, 29 Mar 2011 15:31:19 +0800, Daniel Veillard <veillard@redhat.com> wrote:
On Tue, Mar 29, 2011 at 02:32:18PM +0800, Osier Yang wrote:
Example of cputune XML: <cputune> <shares>2048</shares> <vcpupin vcpu='0' cpuset='0-4,^1'/> <vcpupin vcpu='1' cpuset='1,3'/> <vcpupin vcpu='2' cpuset='0,2'/> </cputune>
"shares" is to define the the proportional weighted cpu share for the domain.
Hum, what does "2048" there means ? I assume there is an unit but it's not defined. Can we get a precide definition of the semantic of the shares construct. If I were to use it I need to know what it means, and I can't just from that description. Drivers in QEmu and LXC just pass that down to linux, but it still doesn't provide a semantic for it and "whatever linux implements at the time" is not really a good answer.
The number is relative wrt other domains/cgroup, so if we have two VMs each having 2048, both of them will get equal share, i.e. 50% each. In a different scenario, if we have VM1's share as 1024 and VM2's share as 2048, that translates as VM1=33% and VM2=66% share of the CPU. Regards Nikunj