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Message-ID: <Zw8QZowkIRM-8-U1@LQ3V64L9R2>
Date: Tue, 15 Oct 2024 18:01:26 -0700
From: Joe Damato <jdamato@...tly.com>
To: Kurt Kanzenbach <kurt@...utronix.de>
Cc: netdev@...r.kernel.org, vinicius.gomes@...el.com,
Tony Nguyen <anthony.l.nguyen@...el.com>,
Przemek Kitszel <przemyslaw.kitszel@...el.com>,
"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: [RFC net-next v2 2/2] igc: Link queues to NAPI instances
On Tue, Oct 15, 2024 at 12:27:01PM +0200, Kurt Kanzenbach wrote:
> On Mon Oct 14 2024, 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>
> > ---
> > 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);
> > + }
> > + }
> > +}
>
> In addition, to what Vinicius said. I think this can be done
> simpler. Something like this?
>
> void igc_set_queue_napi(struct igc_adapter *adapter, int vector,
> struct napi_struct *napi)
> {
> struct igc_q_vector *q_vector = adapter->q_vector[vector];
>
> if (q_vector->rx.ring)
> netif_queue_set_napi(adapter->netdev, vector, NETDEV_QUEUE_TYPE_RX, napi);
>
> if (q_vector->tx.ring)
> netif_queue_set_napi(adapter->netdev, vector, NETDEV_QUEUE_TYPE_TX, napi);
> }
Ah, yes, that is much simpler. Thanks for the suggestion. I'll do
that for the v3.
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