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Re: [Xen-devel] [BUG] mistakenly wake in Xen's credit scheduler



On 10/28/2015 06:54 AM, Dario Faggioli wrote:
On Tue, 2015-10-27 at 14:11 -0600, suokun wrote:
On Tue, Oct 27, 2015 at 3:44 AM, George Dunlap <dunlapg@xxxxxxxxx>
wrote:
On Tue, Oct 27, 2015 at 5:59 AM, suokun <suokunstar@xxxxxxxxx>
wrote:

Thank you for your reply. I have test credit2 this morning. The I/O
performance is correct, however, the CPU accounting seems not
correct.
Here is my experiment on credit2:

VM-IO:          1-vCPU pinned to a pCPU, running netperf
VM-CPU:      1-vCPU pinned the the same pCPU, running a while(1) loop
The throughput of netperf is the same(941Mbps) as VM-IO runs alone.

However, when I use xl top to show the VM CPU utilization, VM-IO
takes
73% of CPU time and VM-CPU takes 99% CPU time. Their sum is more than
100%. I doubt it is due to the CPU utilization accounting in credit2
scheduler.

Yeah, well, sorry, but even if we both (me and George) encouraged you
to try Credit2, that wasn't a great idea. :-(  In fact, you're using
pinning for this test, and Credit2 does not have pinning (yet)! :-P

That explains why utilizations are summing up to higher than 100%:
vCPUs are just not being confined to one processor.

Pinning for Credit2 is just around the corner. Let's try this again
when it will be there, ok? :-D

Or try it in a cpupool with just one pcpu?


Juergen

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