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

[Juergen Gross <jgross@xxxxxxxx>]

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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