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SubjectRe: [PATCHSET x86/core/percpu] improve the first percpu chunk allocation
Hello, Ingo.

Ingo Molnar wrote:
> * Tejun Heo <tj@kernel.org> wrote:
>
>>> and i think that abstraction is wrong.
>> No, it's not wrong. It simply is irrelevant - it's congruent
>> vs. contiguos and all that we need is congruent. Contiguous
>> of course achieves congruent but it doesn't make any
>> difference for this purpose.
>
> Well, as long as we can go up in unit size to 2MB (on 64-bit
> x86) i'm fine with that model.

Yeap, it defintely can.

> There's no granularity artifacts, right? pcpu_populate_chunk()
> intelligently only populates pages on an as-needed basis, so
> extending the percpu areas with a 2MB unit does not trigger
> nr_cpus*2MB allocations straight away.

Yeap, it doesn't although reclamation is done per-chunk currently.

> The code looks very clean and if we can agree on the SMP/NUMA
> symmetry and the dynamic-ptr optimizations that it allows, plus
> if you can up the unit size to 2MB on 64-bit x86, i'm a happy
> camper and will pull it.

Sounds good. Thanks.

--
tejun


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