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Message-ID: <5febc201-0bbf-bb08-2bde-7ada5b356740@intel.com>
Date: Tue, 12 Nov 2024 17:06:20 +0200
From: Avigail Dahan <Avigailx.dahan@...el.com>
To: Joe Damato <jdamato@...tly.com>, <netdev@...r.kernel.org>
CC: <vitaly.lifshits@...el.com>, <jacob.e.keller@...el.com>,
<kurt@...utronix.de>, <vinicius.gomes@...el.com>, Tony Nguyen
<anthony.l.nguyen@...el.com>, Przemek Kitszel <przemyslaw.kitszel@...el.com>,
Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, "Paolo
Abeni" <pabeni@...hat.com>, Alexei Starovoitov <ast@...nel.org>, "Daniel
Borkmann" <daniel@...earbox.net>, Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>, "moderated list:INTEL ETHERNET
DRIVERS" <intel-wired-lan@...ts.osuosl.org>, open list
<linux-kernel@...r.kernel.org>, "open list:XDP (eXpress Data Path)"
<bpf@...r.kernel.org>
Subject: Re: [Intel-wired-lan] [PATCH iwl-next v6 2/2] igc: Link queues to
NAPI instances
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@...tly.com>
> Reviewed-by: Vitaly Lifshits <vitaly.lifshits@...el.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@...el.com>
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