linux-kernel - Re: [PATCH 3/3] net: mana: add a function to spread IRQs per CPUs

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Message-ID: <9ba04aef-ba13-4366-8709-ea1808dd4270@intel.com>
Date: Mon, 18 Dec 2023 13:17:53 -0800
From: Jacob Keller <jacob.e.keller@...el.com>
To: Yury Norov <yury.norov@...il.com>, Souradeep Chakrabarti
	<schakrabarti@...ux.microsoft.com>, <kys@...rosoft.com>,
	<haiyangz@...rosoft.com>, <wei.liu@...nel.org>, <decui@...rosoft.com>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <longli@...rosoft.com>, <leon@...nel.org>,
	<cai.huoqing@...ux.dev>, <ssengar@...ux.microsoft.com>,
	<vkuznets@...hat.com>, <tglx@...utronix.de>, <linux-hyperv@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-rdma@...r.kernel.org>
CC: <schakrabarti@...rosoft.com>, <paulros@...rosoft.com>
Subject: Re: [PATCH 3/3] net: mana: add a function to spread IRQs per CPUs



On 12/17/2023 1:32 PM, Yury Norov wrote:
> +static __maybe_unused int irq_setup(unsigned int *irqs, unsigned int len, int node)
> +{
> +	const struct cpumask *next, *prev = cpu_none_mask;
> +	cpumask_var_t cpus __free(free_cpumask_var);
> +	int cpu, weight;
> +
> +	if (!alloc_cpumask_var(&cpus, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	rcu_read_lock();
> +	for_each_numa_hop_mask(next, node) {
> +		weight = cpumask_weight_andnot(next, prev);
> +		while (weight-- > 0) {
> +			cpumask_andnot(cpus, next, prev);
> +			for_each_cpu(cpu, cpus) {
> +				if (len-- == 0)
> +					goto done;
> +				irq_set_affinity_and_hint(*irqs++, topology_sibling_cpumask(cpu));
> +				cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
> +			}
> +		}
> +		prev = next;
> +	}
> +done:
> +	rcu_read_unlock();
> +	return 0;
> +}
> +

You're adding a function here but its not called and even marked as
__maybe_unused?

>  static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  {
>  	unsigned int max_queues_per_port = num_online_cpus();