Re: [PATCH 0/5] mm/vma: make more mmap logic userland testable

[Lorenzo Stoakes]

On Wed, Dec 04, 2024 at 11:56:32PM +0000, Wei Yang wrote:
> On Tue, Dec 03, 2024 at 06:05:07PM +0000, Lorenzo Stoakes wrote:
> >This series carries on the work the work started in previous series and
>                         ^^^      ^^^
>
> Duplicated?

Thanks yes, but trivial enough that I'm not sure it's worth a
correction. Will fix if need to respin.

>
> >continued in commit 52956b0d7fb9 ("mm: isolate mmap internal logic to
> >mm/vma.c"), moving the remainder of memory mapping implementation details
> >logic into mm/vma.c allowing the bulk of the mapping logic to be unit
> >tested.
> >
> >It is highly useful to do so, as this means we can both fundamentally test
> >this core logic, and introduce regression tests to ensure any issues
> >previously resolved do not recur.
> >
> >Vitally, this includes the do_brk_flags() function, meaning we have both
> >core means of userland mapping memory now testable.
> >
> >Performance testing was performed after this change given the brk() system
> >call's sensitivity to change, and no performance regression was observed.
>
> May I ask what performance test is done?

mmtests brk1, brk2 (will-it-scale)

You'd not really expect an impact based on relocation of this code, but
with brk it's always worth checking...

>
>
> --
> Wei Yang
> Help you, Help me