linux-kernel - Re: [PATCH net-next v3 3/3] net: stmmac: Introducing support for Page Pool

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Date:   Fri, 5 Jul 2019 16:29:05 +0300
From:   Ilias Apalodimas <ilias.apalodimas@...aro.org>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH net-next v3 3/3] net: stmmac: Introducing support for
 Page Pool

Hi Jose,

I think this look ok for now. One request though, on page_pool_free 

On Fri, Jul 05, 2019 at 09:23:00AM +0200, Jose Abreu wrote:
> Mapping and unmapping DMA region is an high bottleneck in stmmac driver,
> specially in the RX path.
> 
> This commit introduces support for Page Pool API and uses it in all RX
> queues. With this change, we get more stable troughput and some increase
> of banwidth with iperf:
> 	- MAC1000 - 950 Mbps
> 	- XGMAC: 9.22 Gbps
> 
> Changes from v2:
> 	- Uncoditionally call page_pool_free() (Jesper)
> Changes from v1:
> 	- Use page_pool_get_dma_addr() (Jesper)
> 	- Add a comment (Jesper)
> 	- Add page_pool_free() call (Jesper)
> 	- Reintroduce sync_single_for_device (Arnd / Ilias)
> 
> Signed-off-by: Jose Abreu <joabreu@...opsys.com>
> Cc: Joao Pinto <jpinto@...opsys.com>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: Giuseppe Cavallaro <peppe.cavallaro@...com>
> Cc: Alexandre Torgue <alexandre.torgue@...com>
> Cc: Ilias Apalodimas <ilias.apalodimas@...aro.org>
> Cc: Jesper Dangaard Brouer <brouer@...hat.com>
> Cc: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/net/ethernet/stmicro/stmmac/Kconfig       |   1 +
>  drivers/net/ethernet/stmicro/stmmac/stmmac.h      |  10 +-
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 203 +++++++---------------
>  3 files changed, 70 insertions(+), 144 deletions(-)
> 

[...]
> @@ -1498,8 +1480,11 @@ static void free_dma_rx_desc_resources(struct stmmac_priv *priv)
>  					  sizeof(struct dma_extended_desc),
>  					  rx_q->dma_erx, rx_q->dma_rx_phy);
>  
> -		kfree(rx_q->rx_skbuff_dma);
> -		kfree(rx_q->rx_skbuff);
> +		kfree(rx_q->buf_pool);
> +		if (rx_q->page_pool) {
> +			page_pool_request_shutdown(rx_q->page_pool);
> +			page_pool_free(rx_q->page_pool);

A patch currently under review will slightly change that [1] and [2]
Can you defer this a bit till that one gets merged?
The only thing you'll have to do is respin this and replace page_pool_free()
with page_pool_destroy()

[1] https://lore.kernel.org/netdev/20190705094346.13b06da6@carbon/
[2] https://lore.kernel.org/netdev/156225871578.1603.6630229522953924907.stgit@firesoul/