Re: [PATCH net-next] net: mana: Force full-page RX buffers for 4K page size on specific systems.

[Paolo Abeni <pabeni@redhat.com>]

On 2/27/26 11:15 AM, Dipayaan Roy wrote:
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index 91c418097284..a53a8921050b 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -748,6 +748,26 @@ static void *mana_get_rxbuf_pre(struct mana_rxq *rxq, dma_addr_t *da)
>  	return va;
>  }
>  
> +static inline bool
> +mana_use_single_rxbuf_per_page(struct mana_port_context *apc, u32 mtu)
> +{

I almost forgot: please avoid the 'inline' keyword in .c files. This is
function used only once, should be inlined by the compiler anyway.

> +	struct gdma_context *gc = apc->ac->gdma_dev->gdma_context;
> +
> +	/* On some systems with 4K PAGE_SIZE, page_pool RX fragments can
> +	 * trigger a throughput regression. Hence forces one RX buffer per page
> +	 * to avoid the fragment allocation/refcounting overhead in the RX
> +	 * refill path for those processors only.
> +	 */
> +	if (gc->force_full_page_rx_buffer)
> +		return true;

Side note: since you could keep the above flag up2date according to the
current mtu and xdp configuration and just test it in the data path.

/P