linux-kernel - Re: [PATCH v2] enic: add ethtool get

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Date: Tue, 25 Jun 2024 17:03:25 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Jon Kohler <jon@...anix.com>
Cc: Christian Benvenuti <benve@...co.com>, Satish Kharat
 <satishkh@...co.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] enic: add ethtool get_channel support

On Mon, 24 Jun 2024 11:49:00 -0700 Jon Kohler wrote:
> +	switch (vnic_dev_get_intr_mode(enic->vdev)) {
> +	case VNIC_DEV_INTR_MODE_MSIX:
> +		channels->max_rx = ENIC_RQ_MAX;
> +		channels->max_tx = ENIC_WQ_MAX;
> +		channels->rx_count = enic->rq_count;
> +		channels->tx_count = enic->wq_count;
> +		break;
> +	case VNIC_DEV_INTR_MODE_MSI:
> +		channels->max_rx = 1;
> +		channels->max_tx = 1;
> +		channels->rx_count = 1;
> +		channels->tx_count = 1;
> +		break;
> +	case VNIC_DEV_INTR_MODE_INTX:
> +		channels->max_combined = 1;
> +		channels->combined_count = 1;
> +	default:
> +		break;
> +	}

sorry for not responding properly to your earlier email, but I think
MSI should also be combined. What matters is whether the IRQ serves
just one of {Rx, Tx} or both.

For MSI, I see:

1 . enic_dev_init() does:
	netif_napi_add(netdev, &enic->napi[0], enic_poll);
                                               ^^^^^^^^^

2. enic_request_intr() does
	request_irq(enic->pdev->irq, enic_isr_msi, ...
                                     ^^^^^^^^^^^^

3. enic_isr_msi() does 
	napi_schedule_irqoff(&enic->napi[0]); 
thus matching the NAPI from step #1.

4. enic_poll() calls both enic_wq_service, and enic_rq_service

So it's combined, AFAICT, similar to INTX in the relevant parts.
-- 
pw-bot: cr