Re: [RFC net-next v2 2/2] igc: Link queues to NAPI instances

[Vinicius Costa Gomes <vinicius.gomes@intel.com>]

Joe Damato <jdamato@fastly.com> writes:

> Link queues to NAPI instances via netdev-genl API so that users can
> query this information with netlink. Handle a few cases in the driver:
>   1. Link/unlink the NAPIs when XDP is enabled/disabled
>   2. Handle IGC_FLAG_QUEUE_PAIRS enabled and disabled
>
> Example output when IGC_FLAG_QUEUE_PAIRS is enabled:
>
> $ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
>                          --dump queue-get --json='{"ifindex": 2}'
>
> [{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
>  {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
>  {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'rx'},
>  {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'rx'},
>  {'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'tx'},
>  {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'tx'},
>  {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'tx'},
>  {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'tx'}]
>
> Since IGC_FLAG_QUEUE_PAIRS is enabled, you'll note that the same NAPI ID
> is present for both rx and tx queues at the same index, for example
> index 0:
>
> {'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
> {'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'tx'},
>
> To test IGC_FLAG_QUEUE_PAIRS disabled, a test system was booted using
> the grub command line option "maxcpus=2" to force
> igc_set_interrupt_capability to disable IGC_FLAG_QUEUE_PAIRS.
>
> Example output when IGC_FLAG_QUEUE_PAIRS is disabled:
>
> $ lscpu | grep "On-line CPU"
> On-line CPU(s) list:      0,2
>
> $ ethtool -l enp86s0  | tail -5
> Current hardware settings:
> RX:		n/a
> TX:		n/a
> Other:		1
> Combined:	2
>
> $ cat /proc/interrupts  | grep enp
>  144: [...] enp86s0
>  145: [...] enp86s0-rx-0
>  146: [...] enp86s0-rx-1
>  147: [...] enp86s0-tx-0
>  148: [...] enp86s0-tx-1
>
> 1 "other" IRQ, and 2 IRQs for each of RX and Tx, so we expect netlink to
> report 4 IRQs with unique NAPI IDs:
>
> $ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
>                          --dump napi-get --json='{"ifindex": 2}'
> [{'id': 8196, 'ifindex': 2, 'irq': 148},
>  {'id': 8195, 'ifindex': 2, 'irq': 147},
>  {'id': 8194, 'ifindex': 2, 'irq': 146},
>  {'id': 8193, 'ifindex': 2, 'irq': 145}]
>
> Now we examine which queues these NAPIs are associated with, expecting
> that since IGC_FLAG_QUEUE_PAIRS is disabled each RX and TX queue will
> have its own NAPI instance:
>
> $ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
>                          --dump queue-get --json='{"ifindex": 2}'
> [{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
>  {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
>  {'id': 0, 'ifindex': 2, 'napi-id': 8195, 'type': 'tx'},
>  {'id': 1, 'ifindex': 2, 'napi-id': 8196, 'type': 'tx'}]
>
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---
>  v2:
>    - Update commit message to include tests for IGC_FLAG_QUEUE_PAIRS
>      disabled
>    - Refactored code to move napi queue mapping and unmapping to helper
>      functions igc_set_queue_napi and igc_unset_queue_napi
>    - Adjust the code to handle IGC_FLAG_QUEUE_PAIRS disabled
>    - Call helpers to map/unmap queues to NAPIs in igc_up, __igc_open,
>      igc_xdp_enable_pool, and igc_xdp_disable_pool
>
>  drivers/net/ethernet/intel/igc/igc.h      |  3 ++
>  drivers/net/ethernet/intel/igc/igc_main.c | 58 +++++++++++++++++++++--
>  drivers/net/ethernet/intel/igc/igc_xdp.c  |  2 +
>  3 files changed, 59 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
> index eac0f966e0e4..7b1c9ea60056 100644
> --- a/drivers/net/ethernet/intel/igc/igc.h
> +++ b/drivers/net/ethernet/intel/igc/igc.h
> @@ -337,6 +337,9 @@ struct igc_adapter {
>  	struct igc_led_classdev *leds;
>  };
>  
> +void igc_set_queue_napi(struct igc_adapter *adapter, int q_idx,
> +			struct napi_struct *napi);
> +void igc_unset_queue_napi(struct igc_adapter *adapter, int q_idx);
>  void igc_up(struct igc_adapter *adapter);
>  void igc_down(struct igc_adapter *adapter);
>  int igc_open(struct net_device *netdev);
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 7964bbedb16c..59c00acfa0ed 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -4948,6 +4948,47 @@ static int igc_sw_init(struct igc_adapter *adapter)
>  	return 0;
>  }
>  
> +void igc_set_queue_napi(struct igc_adapter *adapter, int q_idx,
> +			struct napi_struct *napi)
> +{
> +	if (adapter->flags & IGC_FLAG_QUEUE_PAIRS) {
> +		netif_queue_set_napi(adapter->netdev, q_idx,
> +				     NETDEV_QUEUE_TYPE_RX, napi);
> +		netif_queue_set_napi(adapter->netdev, q_idx,
> +				     NETDEV_QUEUE_TYPE_TX, napi);
> +	} else {
> +		if (q_idx < adapter->num_rx_queues) {
> +			netif_queue_set_napi(adapter->netdev, q_idx,
> +					     NETDEV_QUEUE_TYPE_RX, napi);
> +		} else {
> +			q_idx -= adapter->num_rx_queues;
> +			netif_queue_set_napi(adapter->netdev, q_idx,
> +					     NETDEV_QUEUE_TYPE_TX, napi);
> +		}
> +	}
> +}
> +
> +void igc_unset_queue_napi(struct igc_adapter *adapter, int q_idx)
> +{
> +	struct net_device *netdev = adapter->netdev;
> +
> +	if (adapter->flags & IGC_FLAG_QUEUE_PAIRS) {
> +		netif_queue_set_napi(netdev, q_idx, NETDEV_QUEUE_TYPE_RX,
> +				     NULL);
> +		netif_queue_set_napi(netdev, q_idx, NETDEV_QUEUE_TYPE_TX,
> +				     NULL);
> +	} else {
> +		if (q_idx < adapter->num_rx_queues) {
> +			netif_queue_set_napi(adapter->netdev, q_idx,
> +					     NETDEV_QUEUE_TYPE_RX, NULL);
> +		} else {
> +			q_idx -= adapter->num_rx_queues;
> +			netif_queue_set_napi(adapter->netdev, q_idx,
> +					     NETDEV_QUEUE_TYPE_TX, NULL);
> +		}
> +	}
> +}

It seems that igc_unset_queue_napi() is igc_set_queue_napi(x, y, NULL),
so I would suggest either implementing "unset" in terms of "set", or
using igc_set_queue_napi(x, y, NULL) directly in the "unlink" case (I
have a slight preference for the second option).

> +
>  /**
>   * igc_up - Open the interface and prepare it to handle traffic
>   * @adapter: board private structure
> @@ -4955,6 +4996,7 @@ static int igc_sw_init(struct igc_adapter *adapter)
>  void igc_up(struct igc_adapter *adapter)
>  {
>  	struct igc_hw *hw = &adapter->hw;
> +	struct napi_struct *napi;
>  	int i = 0;
>  
>  	/* hardware has been reset, we need to reload some things */
> @@ -4962,8 +5004,11 @@ void igc_up(struct igc_adapter *adapter)
>  
>  	clear_bit(__IGC_DOWN, &adapter->state);
>  
> -	for (i = 0; i < adapter->num_q_vectors; i++)
> -		napi_enable(&adapter->q_vector[i]->napi);
> +	for (i = 0; i < adapter->num_q_vectors; i++) {
> +		napi = &adapter->q_vector[i]->napi;
> +		napi_enable(napi);
> +		igc_set_queue_napi(adapter, i, napi);
> +	}
>  
>  	if (adapter->msix_entries)
>  		igc_configure_msix(adapter);
> @@ -5192,6 +5237,7 @@ void igc_down(struct igc_adapter *adapter)
>  	for (i = 0; i < adapter->num_q_vectors; i++) {
>  		if (adapter->q_vector[i]) {
>  			napi_synchronize(&adapter->q_vector[i]->napi);
> +			igc_unset_queue_napi(adapter, i);
>  			napi_disable(&adapter->q_vector[i]->napi);
>  		}
>  	}
> @@ -6021,6 +6067,7 @@ static int __igc_open(struct net_device *netdev, bool resuming)
>  	struct igc_adapter *adapter = netdev_priv(netdev);
>  	struct pci_dev *pdev = adapter->pdev;
>  	struct igc_hw *hw = &adapter->hw;
> +	struct napi_struct *napi;
>  	int err = 0;
>  	int i = 0;
>  
> @@ -6056,8 +6103,11 @@ static int __igc_open(struct net_device *netdev, bool resuming)
>  
>  	clear_bit(__IGC_DOWN, &adapter->state);
>  
> -	for (i = 0; i < adapter->num_q_vectors; i++)
> -		napi_enable(&adapter->q_vector[i]->napi);
> +	for (i = 0; i < adapter->num_q_vectors; i++) {
> +		napi = &adapter->q_vector[i]->napi;
> +		napi_enable(napi);
> +		igc_set_queue_napi(adapter, i, napi);
> +	}
>  
>  	/* Clear any pending interrupts. */
>  	rd32(IGC_ICR);
> diff --git a/drivers/net/ethernet/intel/igc/igc_xdp.c b/drivers/net/ethernet/intel/igc/igc_xdp.c
> index e27af72aada8..886f04b8c394 100644
> --- a/drivers/net/ethernet/intel/igc/igc_xdp.c
> +++ b/drivers/net/ethernet/intel/igc/igc_xdp.c
> @@ -84,6 +84,7 @@ static int igc_xdp_enable_pool(struct igc_adapter *adapter,
>  		napi_disable(napi);
>  	}
>  
> +	igc_unset_queue_napi(adapter, queue_id);
>  	set_bit(IGC_RING_FLAG_AF_XDP_ZC, &rx_ring->flags);
>  	set_bit(IGC_RING_FLAG_AF_XDP_ZC, &tx_ring->flags);
>  
> @@ -133,6 +134,7 @@ static int igc_xdp_disable_pool(struct igc_adapter *adapter, u16 queue_id)
>  	xsk_pool_dma_unmap(pool, IGC_RX_DMA_ATTR);
>  	clear_bit(IGC_RING_FLAG_AF_XDP_ZC, &rx_ring->flags);
>  	clear_bit(IGC_RING_FLAG_AF_XDP_ZC, &tx_ring->flags);
> +	igc_set_queue_napi(adapter, queue_id, napi);
>  
>  	if (needs_reset) {
>  		napi_enable(napi);
> -- 
> 2.25.1
>


Cheers,
-- 
Vinicius