使用NVMe driver的poll_queues参数即可开启IO queue的poll。

内核源码

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//https://elixir.bootlin.com/linux/v6.0/source/drivers/nvme/host/pci.c
static unsigned int poll_queues;
module_param_cb(poll_queues, &io_queue_count_ops, &poll_queues, 0644);
MODULE_PARM_DESC(poll_queues, "Number of queues to use for polled IO.");
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static int nvme_setup_io_queues(struct nvme_dev *dev)
{
	...
	dev->nr_poll_queues = poll_queues;
	...
}

注意事项

当只有一个IO queue时，设置poll_queues为1后，发现依然有中断。其实这是符合预取的。

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static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues)
{
	struct pci_dev *pdev = to_pci_dev(dev->dev);
	struct irq_affinity affd = {
		.pre_vectors	= 1,
		.calc_sets	= nvme_calc_irq_sets,
		.priv		= dev,
	};
	unsigned int irq_queues, poll_queues;

	/*
	 * Poll queues don't need interrupts, but we need at least one I/O queue
	 * left over for non-polled I/O.
	 */
	poll_queues = min(dev->nr_poll_queues, nr_io_queues - 1);
	dev->io_queues[HCTX_TYPE_POLL] = poll_queues;

	/*
	 * Initialize for the single interrupt case, will be updated in
	 * nvme_calc_irq_sets().
	 */
	dev->io_queues[HCTX_TYPE_DEFAULT] = 1;
	dev->io_queues[HCTX_TYPE_READ] = 0;

	/*
	 * We need interrupts for the admin queue and each non-polled I/O queue,
	 * but some Apple controllers require all queues to use the first
	 * vector.
	 */
	irq_queues = 1;
	if (!(dev->ctrl.quirks & NVME_QUIRK_SINGLE_VECTOR))
		irq_queues += (nr_io_queues - poll_queues);
	return pci_alloc_irq_vectors_affinity(pdev, 1, irq_queues,
			      PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
}

由上述代码可知，driver至少留一个IO queue使用interrupt而非poll。

因此，当只有一个IO queue时，即使driver参数设置了poll_queues为1，其实是不生效的(nvme_setup_irqs中的poll_queues变量为0)，这个唯一的IO queue使用的依然是interrupt而非poll。