Re: [PATCH] mm/hugetlb: Concentrated releases memory when cmdline specifies node requests for large pages

[Su Hua <suhua.tanke@gmail.com>]

It does seem to be for a newly allocated huge page just call
enqueue_hugetlb_folio without the complicated decisions in
free_huge_folio.

Thanks
Su

Muchun Song <muchun.song@linux.dev> 于2024年10月12日周六 11:23写道：
>
>
>
> > On Oct 11, 2024, at 16:05, suhua <suhua.tanke@gmail.com> wrote:
> >
> > When HVO is enabled and huge page memory allocs are made, the freed memory
> > can be aggregated into higher order memory in the following paths, which
> > facilitates further allocs for higher order memory.
> >
> > echo 200000 > /proc/sys/vm/nr_hugepages
> > echo 200000 > /sys/devices/system/node/node*/hugepages/hugepages-2048kB/nr_hugepages
> > grub： default_hugepagesz=2M hugepagesz=2M hugepages=200000
> >
> > Currently not support for releasing aggregations to higher order in the
> > following way, which will releasing to lower order.
> >
> > grub: default_hugepagesz=2M hugepagesz=2M hugepages=0:100000,1:100000
> >
> > This patch supports the release of huge page optimizations aggregates to
> > higher order memory.
> >
> > eg:
> > cat /proc/cmdline
> > BOOT_IMAGE=/boot/vmlinuz-xxx ... default_hugepagesz=2M hugepagesz=2M hugepages=0:100000,1:100000
> >
> > Before:
> > Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
> > ...
> > Node    0, zone   Normal, type    Unmovable  55282  97039  99307      0      1      1      0      1      1      1      0
> > Node    0, zone   Normal, type      Movable     25     11    345     87     48     21      2     20      9      3  75061
> > Node    0, zone   Normal, type  Reclaimable      4      2      2      4      3      0      2      1      1      1      0
> > Node    0, zone   Normal, type   HighAtomic      0      0      0      0      0      0      0      0      0      0      0
> > ...
> > Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
> > Node    1, zone   Normal, type    Unmovable  98888  99650  99679      2      3      1      2      2      2      0      0
> > Node    1, zone   Normal, type      Movable      1      1      0      1      1      0      1      0      1      1  75937
> > Node    1, zone   Normal, type  Reclaimable      0      0      0      0      0      0      0      0      0      0      0
> > Node    1, zone   Normal, type   HighAtomic      0      0      0      0      0      0      0      0      0      0      0
> >
> > After:
> > Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
> > ...
> > Node    0, zone   Normal, type    Unmovable    152    158     37      2      2      0      3      4      2      6    717
> > Node    0, zone   Normal, type      Movable      1     37     53      3     55     49     16      6      2      1  75000
> > Node    0, zone   Normal, type  Reclaimable      1      4      3      1      2      1      1      1      1      1      0
> > Node    0, zone   Normal, type   HighAtomic      0      0      0      0      0      0      0      0      0      0      0
> > ...
> > Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
> > Node    1, zone   Normal, type    Unmovable      5      3      2      1      3      4      2      2      2      0    779
> > Node    1, zone   Normal, type      Movable      1      0      1      1      1      0      1      0      1      1  75849
> > Node    1, zone   Normal, type  Reclaimable      0      0      0      0      0      0      0      0      0      0      0
> > Node    1, zone   Normal, type   HighAtomic      0      0      0      0      0      0      0      0      0      0      0
>
> A good result. But the subject could be changed to:
>
>         "mm/hugetlb: perform vmemmap optimization batchly for specific node allocation"
>
> >
> > Signed-off-by: suhua <suhua1@kingsoft.com>
> > ---
> > mm/hugetlb.c | 37 +++++++++++++++++++++++++++++++++----
> > 1 file changed, 33 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 190fa05635f4..3441d380c90b 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -2077,6 +2077,24 @@ static struct folio *only_alloc_fresh_hugetlb_folio(struct hstate *h,
> >       return folio;
> > }
> >
> > +static struct folio *only_alloc_and_account_fresh_hugetlb_folio(
> > +             struct hstate *h, gfp_t gfp_mask,
> > +             int nid, nodemask_t *nmask)
> > +{
> > +     struct folio *folio;
> > +
> > +     folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL);
> > +     if (!folio)
> > +             return NULL;
> > +
> > +     spin_lock_irq(&hugetlb_lock);
> > +     h->nr_huge_pages++;
> > +     h->nr_huge_pages_node[nid]++;
> > +     spin_unlock_irq(&hugetlb_lock);
> > +
> > +     return folio;
> > +}
> > +
> > /*
> >  * Common helper to allocate a fresh hugetlb page. All specific allocators
> >  * should use this function to get new hugetlb pages
> > @@ -3301,23 +3319,34 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
> > {
> >       unsigned long i;
> >       char buf[32];
> > +     LIST_HEAD(folio_list);
> > +     struct folio *folio, *tmp_f;
> >
> >       for (i = 0; i < h->max_huge_pages_node[nid]; ++i) {
> >               if (hstate_is_gigantic(h)) {
> >                       if (!alloc_bootmem_huge_page(h, nid))
> >                               break;
> >               } else {
> > -                     struct folio *folio;
> >                       gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
> >
> > -                     folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid,
> > -                                     &node_states[N_MEMORY]);
> > +                     folio = only_alloc_and_account_fresh_hugetlb_folio(h,
> > +                                     gfp_mask, nid, &node_states[N_MEMORY]);
>
> I think we could use only_alloc_fresh_hugetlb_folio plus prep_and_add_allocated_folios
> to achieve the same goal but more simpler, right?
>
> >                       if (!folio)
> >                               break;
> > -                     free_huge_folio(folio); /* free it into the hugepage allocator */
> > +                     list_add(&folio->lru, &folio_list);
> >               }
> >               cond_resched();
> >       }
> > +
> > +     if (!list_empty(&folio_list)) {
> > +             /* Send list for bulk vmemmap optimization processing */
> > +             hugetlb_vmemmap_optimize_folios(h, &folio_list);
> > +
> > +             list_for_each_entry_safe(folio, tmp_f, &folio_list, lru) {
> > +                     free_huge_folio(folio); /* free it into the hugepage allocator */
> > +             }
> > +     }
>
> We could use prep_and_add_allocated_folios here.
>
> Thanks.
>
> > +
> >       if (i == h->max_huge_pages_node[nid])
> >               return;
> >
> > --
> > 2.34.1
> >
>