[PATCH net-next] net: stmmac: Fix page pool size

[PATCH net-next] net: stmmac: Fix page pool size

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

The size of individual pages in the page pool in given by an order. The
order is the binary logarithm of the number of pages that make up one of
the pages in the pool. However, the driver currently passes the number
of pages rather than the order, so it ends up wasting quite a bit of
memory.

Fix this by taking the binary logarithm and passing that in the order
field.

Fixes: 2af6106ae949 ("net: stmmac: Introducing support for Page Pool")
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ecd461207dbc..f8c90dba6db8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1550,13 +1550,15 @@ static int alloc_dma_rx_desc_resources(struct stmmac_priv *priv)
 	for (queue = 0; queue < rx_count; queue++) {
 		struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
 		struct page_pool_params pp_params = { 0 };
+		unsigned int num_pages;
 
 		rx_q->queue_index = queue;
 		rx_q->priv_data = priv;
 
 		pp_params.flags = PP_FLAG_DMA_MAP;
 		pp_params.pool_size = DMA_RX_SIZE;
-		pp_params.order = DIV_ROUND_UP(priv->dma_buf_sz, PAGE_SIZE);
+		num_pages = DIV_ROUND_UP(priv->dma_buf_sz, PAGE_SIZE);
+		pp_params.order = ilog2(num_pages);
 		pp_params.nid = dev_to_node(priv->device);
 		pp_params.dev = priv->device;
 		pp_params.dma_dir = DMA_FROM_DEVICE;
-- 
2.23.0

Re: [PATCH net-next] net: stmmac: Fix page pool size

[Thierry Reding]

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On Mon, Sep 23, 2019 at 11:59:15AM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> The size of individual pages in the page pool in given by an order. The
> order is the binary logarithm of the number of pages that make up one of
> the pages in the pool. However, the driver currently passes the number
> of pages rather than the order, so it ends up wasting quite a bit of
> memory.
> 
> Fix this by taking the binary logarithm and passing that in the order
> field.
> 
> Fixes: 2af6106ae949 ("net: stmmac: Introducing support for Page Pool")
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

I fumbled the git format-patch incantation. This should've been marked
v2.

Thierry

> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index ecd461207dbc..f8c90dba6db8 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1550,13 +1550,15 @@ static int alloc_dma_rx_desc_resources(struct stmmac_priv *priv)
>  	for (queue = 0; queue < rx_count; queue++) {
>  		struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
>  		struct page_pool_params pp_params = { 0 };
> +		unsigned int num_pages;
>  
>  		rx_q->queue_index = queue;
>  		rx_q->priv_data = priv;
>  
>  		pp_params.flags = PP_FLAG_DMA_MAP;
>  		pp_params.pool_size = DMA_RX_SIZE;
> -		pp_params.order = DIV_ROUND_UP(priv->dma_buf_sz, PAGE_SIZE);
> +		num_pages = DIV_ROUND_UP(priv->dma_buf_sz, PAGE_SIZE);
> +		pp_params.order = ilog2(num_pages);
>  		pp_params.nid = dev_to_node(priv->device);
>  		pp_params.dev = priv->device;
>  		pp_params.dma_dir = DMA_FROM_DEVICE;
> -- 
> 2.23.0
> 

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Re: [PATCH net-next] net: stmmac: Fix page pool size

[David Miller]

From: Thierry Reding <thierry.reding@gmail.com>
Date: Mon, 23 Sep 2019 11:59:15 +0200

> From: Thierry Reding <treding@nvidia.com>
> 
> The size of individual pages in the page pool in given by an order. The
> order is the binary logarithm of the number of pages that make up one of
> the pages in the pool. However, the driver currently passes the number
> of pages rather than the order, so it ends up wasting quite a bit of
> memory.
> 
> Fix this by taking the binary logarithm and passing that in the order
> field.
> 
> Fixes: 2af6106ae949 ("net: stmmac: Introducing support for Page Pool")
> Signed-off-by: Thierry Reding <treding@nvidia.com>

Not only should this have been marked v2, it should have targetted 'net'
instead of 'net-next'.

In any event, I've applied it, thanks.