Re: [Xen-devel] [PATCH v2 2/2] sched_credit2.c: runqueue_per_core code

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.03.15 at 16:26, <george.dunlap@xxxxxxxxxxxxx> wrote:
> In both cases there's a slight risk in using system_state to determine
> whether to rely on cpu_data[] or not, because there's actually a window
> for each processor after system_state == SYS_STATE_smp_boot where
> cpu_data[] is *not* initialized, but it's not obvious from looking at
> the data itself.  If the callback mechanisms ever change order with the
> cpu_data[] initializations in the future, we risk a situation where
> credit2 silently regresses to using a single massive runqueue.

But such an ordering change is extremely unlikely, since the
CPU_STARTING notification specifically tells you that the given
CPU is now ready for normal use, which includes it having its
topology related data set up.

Jan


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