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

[Kefeng Wang <wangkefeng.wang@huawei.com>]

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@huawei.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>   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
> +	while (nr_alloced < nr_pages) {
>   		page = alloc_pages_node(nid, gfp_mask, 0);
>   		if (!page)
>   			goto out;