Re: [Intel-wired-lan] [PATCH iwl-next v6 2/2] igc: Link queues to NAPI instances

[Avigail Dahan <Avigailx.dahan@intel.com>]

On 29/10/2024 22:12, Joe Damato wrote:
> 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>
> Reviewed-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
> ---
>   v6:
>     - Rename __igc_do_resume to __igc_resume and rename the boolean
>       argument "need_rtnl" to "rpm" as seen in igb, as per Vitaly's
>       feedback to make the code look more like commit ac8c58f5b535 ("igb:
>       fix deadlock caused by taking RTNL in RPM resume path").
> 
>   v5:
>     - Rename igc_resume to __igc_do_resume and pass in a boolean
>       "need_rtnl" to signal whether or not rtnl should be held before
>       caling __igc_open. Call this new function from igc_runtime_resume
>       and igc_resume passing in false (for igc_runtime_resume) and true
>       (igc_resume), respectively. This is done to avoid reintroducing a
>       bug fixed in commit: 6f31d6b: "igc: Refactor runtime power
>       management flow" where rtnl is held in runtime_resume causing a
>       deadlock.
> 
>   v4:
>     - Add rtnl_lock/rtnl_unlock in two paths: igc_resume and
>       igc_io_error_detected. The code added to the latter is inspired by
>       a similar implementation in ixgbe's ixgbe_io_error_detected.
> 
>   v3:
>     - Replace igc_unset_queue_napi with igc_set_queue_napi(adapater, i,
>       NULL), as suggested by Vinicius Costa Gomes
>     - Simplify implemention of igc_set_queue_napi as suggested by Kurt
>       Kanzenbach, with a tweak to use ring->queue_index
> 
>   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      |  2 +
>   drivers/net/ethernet/intel/igc/igc_main.c | 56 +++++++++++++++++++----
>   drivers/net/ethernet/intel/igc/igc_xdp.c  |  2 +
>   3 files changed, 51 insertions(+), 9 deletions(-)
> 
Tested-by: Avigail Dahan <avigailx.dahan@intel.com>