| From: |
| Nicolai Buchwitz <nb-AT-tipi-net.de> |
| To: |
| Doug Berger <opendmb-AT-gmail.com>, Florian Fainelli <florian.fainelli-AT-broadcom.com>, bcm-kernel-feedback-list-AT-broadcom.com, Andrew Lunn <andrew+netdev-AT-lunn.ch>, "David S . Miller" <davem-AT-davemloft.net>, Eric Dumazet <edumazet-AT-google.com>, Jakub Kicinski <kuba-AT-kernel.org>, Paolo Abeni <pabeni-AT-redhat.com> |
| Subject: |
| [PATCH net-next 0/3] net: bcmgenet: collapse TX priority queues |
| Date: |
| Fri, 12 Jun 2026 22:59:12 +0200 |
| Message-ID: |
| <20260612205915.3156127-1-nb@tipi-net.de> |
| Cc: |
| Justin Chen <justin.chen-AT-broadcom.com>, Ovidiu Panait <ovidiu.panait.rb-AT-renesas.com>, netdev-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org, Nicolai Buchwitz <nb-AT-tipi-net.de> |
| Archive-link: |
| Article |
The strict-priority TX queues can starve under multi-queue load and
trip NETDEV_WATCHDOG. Justin's earlier series [1] tried to mitigate
the timeouts but kept the multi-queue design. Ovidiu Panait recently
proposed a WRR stop-gap [2]. This series drops the priority queues
entirely. Justin confirmed they are no longer required.
Patch 1 collapses v2-v4 hw_params to the same single-queue path v1
already uses. Patch 2 removes the now-dead priority register writes,
helper macros, and the dead "flow period for ring != 0" branch in
bcmgenet_init_tx_ring(); the DMA_ARBITER_{RR,WRR,SP} and
DMA_RING_BUF_PRIORITY_* HW defines are kept as register
documentation. Patch 3 switches the netdev allocation from
alloc_etherdev_mqs(., 5, 5) to alloc_etherdev(), since only one
TX/RX queue is ever used.
Tested on Raspberry Pi CM4 (BCM2711):
- Ovidiu's reproducer (iperf3 -u -b0 -P16 -t60) no longer trips
NETDEV_WATCHDOG.
- UDP sustains 956 Mbit/s line rate over 60 s with 0 datagrams
lost (0/4952890).
- Single-stream TCP throughput unchanged at 943 Mbit/s.
[1] https://lore.kernel.org/netdev/20260406175756.134567-1-ju...
[2] https://lore.kernel.org/netdev/20260610085238.56300-1-ovi...
Nicolai Buchwitz (3):
net: bcmgenet: collapse TX priority queues to a single queue
net: bcmgenet: remove dead priority queue plumbing
net: bcmgenet: allocate a single-queue netdev
.../net/ethernet/broadcom/genet/bcmgenet.c | 100 +++---------------
.../net/ethernet/broadcom/genet/bcmgenet.h | 2 -
2 files changed, 16 insertions(+), 86 deletions(-)
--
2.53.0
