linux-kernel - Re: [PATCH net 1/9] net/mlx5: Ensure fw pages are always allocated on same NUMA

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Message-ID: <1688e772-3067-4277-ad45-6564b4fbbddf@linux.dev>
Date: Fri, 13 Jun 2025 09:22:27 -0700
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: Mark Bloch <mbloch@...dia.com>, "David S. Miller" <davem@...emloft.net>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Eric Dumazet <edumazet@...gle.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 Simon Horman <horms@...nel.org>
Cc: saeedm@...dia.com, gal@...dia.com, leonro@...dia.com, tariqt@...dia.com,
 Leon Romanovsky <leon@...nel.org>, netdev@...r.kernel.org,
 linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
 Moshe Shemesh <moshe@...dia.com>
Subject: Re: [PATCH net 1/9] net/mlx5: Ensure fw pages are always allocated on
 same NUMA

在 2025/6/10 8:15, Mark Bloch 写道:
> From: Moshe Shemesh <moshe@...dia.com>
> 
> When firmware asks the driver to allocate more pages, using event of
> give_pages, the driver should always allocate it from same NUMA, the
> original device NUMA. Current code uses dev_to_node() which can result
> in different NUMA as it is changed by other driver flows, such as
> mlx5_dma_zalloc_coherent_node(). Instead, use saved numa node for
> allocating firmware pages.

I'm not sure whether NUMA balancing is currently being considered or not.

If I understand correctly, after this commit is applied, all pages will 
be allocated from the same NUMA node — specifically, the original 
device's NUMA node. This seems like it could lead to NUMA imbalance.

By using dev_to_node, it appears that pages could be allocated from 
other NUMA nodes, which might help maintain better NUMA balance.

In the past, I encountered a NUMA balancing issue caused by the mlx5 
NIC, so using dev_to_node might be beneficial in addressing similar 
problems.

Thanks,
Zhu Yanjun

> 
> Fixes: 311c7c71c9bb ("net/mlx5e: Allocate DMA coherent memory on reader NUMA node")
> Signed-off-by: Moshe Shemesh <moshe@...dia.com>
> Reviewed-by: Tariq Toukan <tariqt@...dia.com>
> Signed-off-by: Mark Bloch <mbloch@...dia.com>
> ---
>   drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
> index 972e8e9df585..9bc9bd83c232 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
> @@ -291,7 +291,7 @@ static void free_4k(struct mlx5_core_dev *dev, u64 addr, u32 function)
>   static int alloc_system_page(struct mlx5_core_dev *dev, u32 function)
>   {
>   	struct device *device = mlx5_core_dma_dev(dev);
> -	int nid = dev_to_node(device);
> +	int nid = dev->priv.numa_node;
>   	struct page *page;
>   	u64 zero_addr = 1;
>   	u64 addr;