linux-kernel - Re: [PATCH net-next v15 08/13] mm: page_frag: use __alloc_pages() to replace alloc_pages

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Message-ID: <CAKgT0Ue+6Gke9YguEDiq6whqQg0DdjPjSDDiRHEeVe5MX80+-Q@mail.gmail.com>
Date: Mon, 26 Aug 2024 10:00:27 -0700
From: Alexander Duyck <alexander.duyck@...il.com>
To: Yunsheng Lin <linyunsheng@...wei.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Subject: Re: [PATCH net-next v15 08/13] mm: page_frag: use __alloc_pages() to
 replace alloc_pages_node()

On Mon, Aug 26, 2024 at 5:46 AM Yunsheng Lin <linyunsheng@...wei.com> wrote:
>
> It seems there is about 24Bytes binary size increase for
> __page_frag_cache_refill() after refactoring in arm64 system
> with 64K PAGE_SIZE. By doing the gdb disassembling, It seems
> we can have more than 100Bytes decrease for the binary size
> by using __alloc_pages() to replace alloc_pages_node(), as
> there seems to be some unnecessary checking for nid being
> NUMA_NO_NODE, especially when page_frag is part of the mm
> system.
>
> CC: Alexander Duyck <alexander.duyck@...il.com>
> Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
> ---
>  mm/page_frag_cache.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c
> index bba59c87d478..e0ad3de11249 100644
> --- a/mm/page_frag_cache.c
> +++ b/mm/page_frag_cache.c
> @@ -28,11 +28,11 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
>  #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
>         gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) |  __GFP_COMP |
>                    __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC;
> -       page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
> -                               PAGE_FRAG_CACHE_MAX_ORDER);
> +       page = __alloc_pages(gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER,
> +                            numa_mem_id(), NULL);
>  #endif
>         if (unlikely(!page)) {
> -               page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
> +               page = __alloc_pages(gfp, 0, numa_mem_id(), NULL);
>                 if (unlikely(!page)) {
>                         nc->encoded_page = 0;
>                         return NULL;

I still think this would be better served by fixing alloc_pages_node
to drop the superfluous checks rather than changing the function. We
would get more gain by just addressing the builtin constant and
NUMA_NO_NODE case there.