netdev - Re: [PATCH v2] enic: add ethtool get

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Message-ID: <EF2C8FF1-BD91-4F46-BFE4-D2855A43F739@nutanix.com>
Date: Wed, 26 Jun 2024 00:37:25 +0000
From: Jon Kohler <jon@...anix.com>
To: Jakub Kicinski <kuba@...nel.org>
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"
	<netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] enic: add ethtool get_channel support



> On Jun 25, 2024, at 8:03 PM, Jakub Kicinski <kuba@...nel.org> wrote:
> 
> 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.

Ok, thanks for the tip, I appreciate it. I’ll send out a v3 shortly

> -- 
> pw-bot: cr