Re: [External] Re: [PATCH v8 12/12] mm/hugetlb: Optimize the code with the help of the compiler

Oscar Salvador
2020-12-10T13:17:32Z

On Thu, Dec 10, 2020 at 08:14:18PM +0800, Muchun Song wrote:
> Yeah, you are right. But if we do this check can make the code simple.
>
> For example, here is a code snippet.
>
> void func(void)
> {
> if (free_vmemmap_pages_per_hpage())
> return;
> /* Do something */
> }
>
> With this patch, the func will be optimized to null when is_power_of_2
> returns false.
>
> void func(void)
> {
> }
>
> Without this patch, the compiler cannot do this optimization.

Ok, I misread the changelog.

So, then is_hugetlb_free_vmemmap_enabled, free_huge_page_vmemmap,
free_vmemmap_pages_per_hpage and hugetlb_vmemmap_init are optimized
out, right?

--
Oscar Salvador
SUSE L3