Re: [PATCH] mm: hugetlb_vmemmap: use bulk allocator in alloc_vmemmap_page_list()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

On 2023/9/5 17:23, Muchun Song wrote:
> > On Sep 5, 2023, at 15:32, Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
> > On 2023/9/5 15:10, Kefeng Wang wrote:
> > > It is needed 4095 pages(1G) or 7 pages(2M) to be allocated once in
> > > alloc_vmemmap_page_list(), so let's add a bulk allocator varietas
> > > alloc_pages_bulk_list_node() and switch alloc_vmemmap_page_list()
> > > to use it to accelerate page allocation.
> > > Simple test on arm64's qemu with 1G Hugetlb, 870,842ns vs 3,845,252ns
> > > despite the fluctuations, it is still a nice improvement.
> > > Tested-by: Yuan Can <yuancan@xxxxxxxxxx>
> > > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > > ---
> > >   include/linux/gfp.h  | 9 +++++++++
> > >   mm/hugetlb_vmemmap.c | 7 ++++++-
> > >   2 files changed, 15 insertions(+), 1 deletion(-)
> > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> > > index 665f06675c83..d6e82f15b61f 100644
> > > --- a/include/linux/gfp.h
> > > +++ b/include/linux/gfp.h
> > > @@ -195,6 +195,15 @@ alloc_pages_bulk_list(gfp_t gfp, unsigned long nr_pages, struct list_head *list)
> > >    return __alloc_pages_bulk(gfp, numa_mem_id(), NULL, nr_pages, list, NULL);
> > >   }
> > >   +static inline unsigned long
> > > +alloc_pages_bulk_list_node(gfp_t gfp, int nid, unsigned long nr_pages, struct list_head *list)
> > > +{
> > > + if (nid == NUMA_NO_NODE)
> > > + nid = numa_mem_id();
> > > +
> > > + return __alloc_pages_bulk(gfp, nid, NULL, nr_pages, list, NULL);
> > > +}
> > > +
> > >   static inline unsigned long
> > >   alloc_pages_bulk_array(gfp_t gfp, unsigned long nr_pages, struct page **page_array)
> > >   {
> > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> > > index 4b9734777f69..699c4fea6b9f 100644
> > > --- a/mm/hugetlb_vmemmap.c
> > > +++ b/mm/hugetlb_vmemmap.c
> > > @@ -384,8 +384,13 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
> > >    unsigned long nr_pages = (end - start) >> PAGE_SHIFT;
> > >    int nid = page_to_nid((struct page *)start);
> > >    struct page *page, *next;
> > > + unsigned long nr_alloced;
> > >   - while (nr_pages--) {
> > > + nr_alloced = alloc_pages_bulk_list_node(gfp_mask, nid, nr_pages, list);
> > > + if (!nr_alloced)
> > > + return -ENOMEM;
> > > +
> >
> > eh， forget to inc nr_allocated in the fallback patch， will resend
>
> Do not change the judgement, "nr_pages -= nr_alloced;" is enough
> and simple.

sure, thanks.

> > > + while (nr_alloced < nr_pages) {
> > >    page = alloc_pages_node(nid, gfp_mask, 0);
> > >    if (!page)
> > >    goto out;