Re: [Xen-devel] does cpu_down makes brings core to deepest sleep state?

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.10.15 at 09:59, <hamedrostamzade@xxxxxxxxx> wrote:
> I modified Xen kernel to turn off the core number 1 from 80th second to
> 100th.
> In 80th second I use cpu_down which is implemented in /xen/common/cpu.c to
> turn off the 1st core. But, as you can see in below, the core does not be
> in C4 idle state shile have almost 20 second CC6 state residency.
>  Was the core in this 20 second period turned off ?
> C0 residency demonstrate that in the period CPU 1 was in C0 all the time!
> How it is possible to be in C0 and being in CC6 simultaneously?!

But the C0 numbers didn't change - how did you conclude it was in
C0? Fact is - once offlined, no software statistics are being kept for
a CPU; CC6 statistics are being maintained by (and hence read from
hardware), and hence that number changing seems quite natural.

Jan

> sudo xenpm get-cpuidle-state:
> Max possible C-state: C7
> 
> cpu id               : 0
> total C-states       : 5
> idle time(ms)        : 67008
> C0                   : transition [                   0]
>                        residency  [              100722 ms]
> C1                   : transition [                   0]
>                        residency  [                   0 ms]
> C2                   : transition [                   0]
>                        residency  [                   0 ms]
> C3                   : transition [                   0]
>                        residency  [                   0 ms]
> C4                   : transition [                   0]
>                        residency  [                   0 ms]
> pc2                  : [                   0 ms]
> pc3                  : [                   0 ms]
> pc6                  : [                   0 ms]
> pc7                  : [                   0 ms]
> cc3                  : [                   0 ms]
> cc6                  : [                   0 ms]
> cc7                  : [                   0 ms]
> 
> cpu id               : 1
> total C-states       : 5
> idle time(ms)        : 100722
> C0                   : transition [                   0]
>                        residency  [              100722 ms]
> C1                   : transition [                   0]
>                        residency  [                   0 ms]
> C2                   : transition [                   0]
>                        residency  [                   0 ms]
> C3                   : transition [                   0]
>                        residency  [                   0 ms]
> C4                   : transition [                   0]
>                        residency  [                   0 ms]
> pc2                  : [                   0 ms]
> pc3                  : [                   0 ms]
> pc6                  : [                   0 ms]
> pc7                  : [                   0 ms]
> cc3                  : [                 630 ms]
> cc6                  : [               20113 ms]
> cc7                  : [                   0 ms]




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