netdev - Re: [net-next 2/6] i40e: prefetch struct page of Rx buffer conditionally

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Message-ID: <20200728131423.2430b3f1@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Tue, 28 Jul 2020 13:14:23 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Tony Nguyen <anthony.l.nguyen@...el.com>
Cc:     davem@...emloft.net, Li RongQing <lirongqing@...du.com>,
        netdev@...r.kernel.org, nhorman@...hat.com, sassmann@...hat.com,
        jeffrey.t.kirsher@...el.com,
        Andrew Bowers <andrewx.bowers@...el.com>
Subject: Re: [net-next 2/6] i40e: prefetch struct page of Rx buffer
 conditionally

On Tue, 28 Jul 2020 12:08:38 -0700 Tony Nguyen wrote:
> From: Li RongQing <lirongqing@...du.com>
> 
> page_address() accesses struct page only when WANT_PAGE_VIRTUAL
> or HASHED_PAGE_VIRTUAL is defined, otherwise it returns address
> based on offset, so we prefetch it conditionally
> 
> Signed-off-by: Li RongQing <lirongqing@...du.com>
> Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_txrx.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> index 3e5c566ceb01..5d408fe26063 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> @@ -1953,7 +1953,9 @@ static struct i40e_rx_buffer *i40e_get_rx_buffer(struct i40e_ring *rx_ring,
>  	struct i40e_rx_buffer *rx_buffer;
>  
>  	rx_buffer = i40e_rx_bi(rx_ring, rx_ring->next_to_clean);
> +#if defined(WANT_PAGE_VIRTUAL) || defined(HASHED_PAGE_VIRTUAL)
>  	prefetchw(rx_buffer->page);
> +#endif

Looks like something that belongs in a common header not (potentially
multiple) C sources.