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

[Juergen Gross <jgross@suse.com>]

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@umich.edu>
>> wrote:
>>> On Tue, Oct 27, 2015 at 5:59 AM, suokun <suokunstar@gmail.com>
>>> 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