netdev - Re: [PATCH net-next 3/3] net: page_pool: simplify page recycling condition tests

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Date:   Mon, 25 Jan 2021 20:22:19 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Alexander Lobakin <alobakin@...me>
Cc:     brouer@...hat.com, "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Dexuan Cui <decui@...rosoft.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Marco Elver <elver@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        linux-rdma@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH net-next 3/3] net: page_pool: simplify page recycling
 condition tests

On Mon, 25 Jan 2021 16:47:20 +0000
Alexander Lobakin <alobakin@...me> wrote:

> pool_page_reusable() is a leftover from pre-NUMA-aware times. For now,
> this function is just a redundant wrapper over page_is_pfmemalloc(),
> so Inline it into its sole call site.
> 
> Signed-off-by: Alexander Lobakin <alobakin@...me>
> ---
>  net/core/page_pool.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)

Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>

> 
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index f3c690b8c8e3..ad8b0707af04 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -350,14 +350,6 @@ static bool page_pool_recycle_in_cache(struct page *page,
>  	return true;
>  }
>  
> -/* page is NOT reusable when:
> - * 1) allocated when system is under some pressure. (page_is_pfmemalloc)
> - */
> -static bool pool_page_reusable(struct page_pool *pool, struct page *page)
> -{
> -	return !page_is_pfmemalloc(page);
> -}
> -
>  /* If the page refcnt == 1, this will try to recycle the page.
>   * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
>   * the configured size min(dma_sync_size, pool->max_len).
> @@ -373,9 +365,11 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
>  	 * regular page allocator APIs.
>  	 *
>  	 * refcnt == 1 means page_pool owns page, and can recycle it.
> +	 *
> +	 * page is NOT reusable when allocated when system is under
> +	 * some pressure. (page_is_pfmemalloc)
>  	 */
> -	if (likely(page_ref_count(page) == 1 &&
> -		   pool_page_reusable(pool, page))) {
> +	if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
>  		/* Read barrier done in page_ref_count / READ_ONCE */
>  
>  		if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)



-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer