Re: [RFC net-next 2/2] igc: Link queues to NAPI instances
From: Kurt Kanzenbach
Date: Mon Oct 07 2024 - 05:15:13 EST
Hi Joe,
On Thu Oct 03 2024, Joe Damato wrote:
> Link queues to NAPI instances via netdev-genl API so that users can
> query this information with netlink:
>
> $ ./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 uses only combined queues, 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'},
>
> Signed-off-by: Joe Damato <jdamato@xxxxxxxxxx>
> ---
> drivers/net/ethernet/intel/igc/igc_main.c | 30 ++++++++++++++++++++---
> 1 file changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 7964bbedb16c..b3bd5bf29fa7 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -4955,6 +4955,7 @@ 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 +4963,17 @@ 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 only supports combined queues, so link each NAPI to both
> + * TX and RX
> + */
igc has IGC_FLAG_QUEUE_PAIRS. For example there may be 2 queues
configured, but 4 vectors active (and 4 IRQs). Is your patch working
with that? Can be tested easily with `ethtool -L <inf> combined 2` or
by booting with only 2 CPUs.
Thanks,
Kurt
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