From: Petr Machata petrm@mellanox.com
[ Upstream commit 0fe64023162aef123de2f1993ba13a35a786e1de ]
An MC-aware mode was introduced in commit 7b8195306694 ("mlxsw: spectrum: Configure MC-aware mode on mlxsw ports"). In MC-aware mode, BUM traffic gets a special treatment by being assigned to a separate set of traffic classes 8..15. Pairs of TCs 0 and 8, 1 and 9, etc., are then configured to strictly prioritize the lower-numbered ones. The intention is to prevent BUM traffic from flooding the switch and push out all UC traffic, which would otherwise happen, and instead give UC traffic precedence.
However strictly prioritizing UC traffic has the effect that UC overload pushes out all BUM traffic, such as legitimate ARP queries. These packets are kept in queues for a while, but under sustained UC overload, their lifetime eventually expires and these packets are dropped. That is detrimental to network performance as well.
Therefore configure the MC TCs (8..15) with minimum shaper of 200Mbps (a minimum permitted value) to allow a trickle of necessary control traffic to get through.
Fixes: 7b8195306694 ("mlxsw: spectrum: Configure MC-aware mode on mlxsw ports") Signed-off-by: Petr Machata petrm@mellanox.com Signed-off-by: Ido Schimmel idosch@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- .../net/ethernet/mellanox/mlxsw/spectrum.c | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c index e498ee95baca..4ce45f4c35aa 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c @@ -2750,6 +2750,21 @@ int mlxsw_sp_port_ets_maxrate_set(struct mlxsw_sp_port *mlxsw_sp_port, return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qeec), qeec_pl); }
+static int mlxsw_sp_port_min_bw_set(struct mlxsw_sp_port *mlxsw_sp_port, + enum mlxsw_reg_qeec_hr hr, u8 index, + u8 next_index, u32 minrate) +{ + struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp; + char qeec_pl[MLXSW_REG_QEEC_LEN]; + + mlxsw_reg_qeec_pack(qeec_pl, mlxsw_sp_port->local_port, hr, index, + next_index); + mlxsw_reg_qeec_mise_set(qeec_pl, true); + mlxsw_reg_qeec_min_shaper_rate_set(qeec_pl, minrate); + + return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qeec), qeec_pl); +} + int mlxsw_sp_port_prio_tc_set(struct mlxsw_sp_port *mlxsw_sp_port, u8 switch_prio, u8 tclass) { @@ -2827,6 +2842,16 @@ static int mlxsw_sp_port_ets_init(struct mlxsw_sp_port *mlxsw_sp_port) return err; }
+ /* Configure the min shaper for multicast TCs. */ + for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) { + err = mlxsw_sp_port_min_bw_set(mlxsw_sp_port, + MLXSW_REG_QEEC_HIERARCY_TC, + i + 8, i, + MLXSW_REG_QEEC_MIS_MIN); + if (err) + return err; + } + /* Map all priorities to traffic class 0. */ for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) { err = mlxsw_sp_port_prio_tc_set(mlxsw_sp_port, i, 0);