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SubjectRe: [PATCH v6] Unified trace buffer

On Fri, 26 Sep 2008, Mike Travis wrote:
> Steven Rostedt wrote:
> >> The other thing to consider is using a percpu variable.
> >
> > This structure is allocated on request.
> >
> > -- Steve
>
>
> Ahh, then it would need the yet to be added cpu_alloc() from Christoph.

We can always change this later.

>
> Your best bet then is to allocate based on nr_cpu_ids.

Actually in this case I chose num_possible_cpus(). Reason being is that
later I may add an interface to allow the user to select which CPUs they
want to trace, and this will only allocate a subset of CPU buffers.
(not going to implement that in the first release).

But to lay the ground work, I set a buffers->cpumask to be that of all the
cpus with buffers allocated. For now that mask is set to cpu_possible_map.
Since num_possible_cpus() is defined as cpus_weight_nr(cpu_possible_map)
I figured that was the better choice.

-- Steve



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