I am just trying to understand the basics of Linux scheduler.

  • Is Linux scheduler a Cap based or weight based scheduler?

I was previously using Xen. Now I am moving from Xen to KVM. I read VMs are normal process and thus will follow the scheduling policies of the Linux scheduler. I was previously using Xen's credit scheduler which had the capability to set cap/weight for vms. I am searching for equivalent capability and also basic understanding of the Linux scheduler.

I am using Centos 5.6 . Which still uses 2.6.18. I don't think CFS is present in the kernel I am using.

migrated from stackoverflow.com Jun 25 '11 at 17:03

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  • @sethu: I'm interested in this question because I have an upcoming virtual server project that will likely benefit from a little more knowledge about scheduling possibilities and resource allowances; so I will be doing research on this and perhaps can answer at some point. In the mean time it sounds like some of your terminology is mixed up. Are you perhaps mixing up hypervisor settings with kernel scheduler terms? Are you talking about the scheduler in the host kernel, the hypervisor, or the guest kernels? – Caleb Jun 26 '11 at 20:48

You can find a general description of CFS here. It is not weight/cap based in the sense that it is not based on distributing an execution time quantum among the most fit processes. You might want to read about how nice levels are implemented also, which will make the distinction clear.

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