Re: [Xen-devel] [PATCH v2] xen: credit2: avoid using cpumask_weight() in hot-paths

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

On 29.07.19 13:49, Dario Faggioli wrote:
> cpumask_weight() is known to be expensive. In Credit2, we use it in
> load-balancing, but only for knowing how many CPUs are active in a
> runqueue.
>
> Keeping such count in an integer field of the per-runqueue data
> structure we have, completely avoids the need for cpumask_weight().
>
> While there, remove as much other uses of it as we can, even if not in
> hot-paths.
>
> Signed-off-by: Dario Faggioli <dfaggioli@xxxxxxxx>
> ---
> Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Andrii Anisov <andrii.anisov@xxxxxxxxx>
> ---
> I just realized this patch fell through the cracks! :-O
>
> I sent it quite a while ago, I got some comments from Andrew and
> Andrii, but then never really followed up.
>
> So here we hare!
>
> Changes from v1:
> * nr_cpus is now unsigned
> * coding style (no hard tabs)
> * killed a couple of redundant ASSERT()s
> ---
Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>

--
Sincerely,
Andrii Anisov.

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