Re: [RESEND PATCH v7 10/10] selftests/mm/cow: Add tests for anonymous small-sized THP

[David Hildenbrand]

On 27.11.23 15:02, Ryan Roberts wrote:
> On 22/11/2023 16:29, Ryan Roberts wrote:
> > Add tests similar to the existing PMD-sized THP tests, but which operate
> > on memory backed by (PTE-mapped) small-sized THP. This reuses all the
> > existing infrastructure. If the test suite detects that small-sized THP
> > is not supported by the kernel, the new tests are skipped.
> >
> > Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
> > ---
> >   tools/testing/selftests/mm/cow.c | 71 +++++++++++++++++++++++++++++++-
> >   1 file changed, 70 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
> > index d03c453cfd5c..3efc395c7077 100644
> > --- a/tools/testing/selftests/mm/cow.c
> > +++ b/tools/testing/selftests/mm/cow.c
> > @@ -29,15 +29,49 @@
> >   #include "../../../../mm/gup_test.h"
> >   #include "../kselftest.h"
> >   #include "vm_util.h"
> > +#include "thp_settings.h"
> >
> >   static size_t pagesize;
> >   static int pagemap_fd;
> >   static size_t pmdsize;
> > +static int nr_thpsmallsizes;
> > +static size_t thpsmallsizes[20];
>
> Off the back of some comments David made againt the previous patch [1], I'm
> proposing to rework this a bit so that ALL thp sizes are stored in this array,
> not just the non-PMD-sized sizes. This makes the changes overall a bit smaller
> and easier to understand, I think...
>
> >   static int nr_hugetlbsizes;
> >   static size_t hugetlbsizes[10];
> >   static int gup_fd;
> >   static bool has_huge_zeropage;
> >
> > +static int sz2ord(size_t size)
> > +{
> > +	return __builtin_ctzll(size / pagesize);
> > +}
> > +
> > +static int detect_smallthp_sizes(size_t sizes[], int max)
>
> This changes to detect_thp_sizes() and deposits all sizes in sizes[]

Just what I wanted to propose :) Makes it simpler by removing the 
"small" terminology and just detecting thp sizes.

--
Cheers,

David / dhildenb