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

From: Vinicius Costa Gomes
Date: Mon Oct 14 2024 - 21:52:13 EST

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Joe Damato <jdamato@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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

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In reply to: Joe Damato: "[RFC net-next v2 2/2] igc: Link queues to NAPI instances"
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