On 23.08.2024 01:06, Andrew Cooper wrote:
> Using hweight() is an especially expensive way of determining simply if
> multiple bits are set in a value. Worse, 4 of the 10 hweight() calls in Xen
> are of this form.
>
> Switch to the new multiple_bits_set() helper. This is far more efficient than
> the longhand hweight() algorithm and, owing to its simplicity, likely more
> efficient than even a dedicated instruction on a superscalar processor.
>
> No functional change.
>
> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
Reviewed-by: Jan Beulich <jbeul...@suse.com>
Just to mention it: With the title being sufficiently generic, I half
expected the similar {bitmap,cpumask}_weight() to also be taken care of.
Yet certainly those (and maybe also their ... == 1 forms) can be covered
later.
Jan
