netdev - Re: [PATCH net-next v6 2/5] net: napi: add CPU affinity to napi

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Message-ID: <20250120170312.1af6b7e7@kernel.org>
Date: Mon, 20 Jan 2025 17:03:12 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Ahmed Zaki <ahmed.zaki@...el.com>
Cc: netdev@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
 andrew+netdev@...n.ch, edumazet@...gle.com, horms@...nel.org,
 pabeni@...hat.com, davem@...emloft.net, michael.chan@...adcom.com,
 tariqt@...dia.com, anthony.l.nguyen@...el.com,
 przemyslaw.kitszel@...el.com, jdamato@...tly.com, shayd@...dia.com,
 akpm@...ux-foundation.org, shayagr@...zon.com,
 kalesh-anakkur.purayil@...adcom.com
Subject: Re: [PATCH net-next v6 2/5] net: napi: add CPU affinity to
 napi_config

On Fri, 17 Jan 2025 17:33:32 -0700 Ahmed Zaki wrote:
> A common task for most drivers is to remember the user-set CPU affinity
> to its IRQs. On each netdev reset, the driver should re-assign the
> user's settings to the IRQs.

> @@ -393,8 +394,8 @@ struct napi_struct {
>  	struct list_head	dev_list;
>  	struct hlist_node	napi_hash_node;
>  	int			irq;
> -#ifdef CONFIG_RFS_ACCEL
>  	struct irq_affinity_notify notify;
> +#ifdef CONFIG_RFS_ACCEL

Let's remove the #ifdef completely, one int won't make much difference,
it's ~1% of the whole struct..

> @@ -11585,7 +11606,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
>  {
>  	struct net_device *dev;
>  	size_t napi_config_sz;
> -	unsigned int maxqs;
> +	unsigned int maxqs, i, numa;

nit: reverse xmas tree

>  	BUG_ON(strlen(name) >= sizeof(dev->name));
>  
> @@ -11681,6 +11702,10 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
>  	dev->napi_config = kvzalloc(napi_config_sz, GFP_KERNEL_ACCOUNT);
>  	if (!dev->napi_config)
>  		goto free_all;

nit: empty line here

> +	numa = dev_to_node(&dev->dev);
> +	for (i = 0; i < maxqs; i++)
> +		cpumask_set_cpu(cpumask_local_spread(i, numa),
> +				&dev->napi_config[i].affinity_mask);
>  
>  	strscpy(dev->name, name);
>  	dev->name_assign_type = name_assign_type;