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* [PATCH net 0/4] mlxsw: Enable minimum shaper on MC TCs
@ 2018-10-31  9:56 Ido Schimmel
  2018-10-31  9:56 ` [PATCH net 1/4] mlxsw: reg: QEEC: Add minimum shaper fields Ido Schimmel
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: Ido Schimmel @ 2018-10-31  9:56 UTC (permalink / raw)
  To: netdev@vger.kernel.org
  Cc: davem@davemloft.net, Jiri Pirko, Petr Machata, mlxsw,
	Ido Schimmel

Petr says:

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.

In this patchset, MC TCs (8..15) are configured with minimum shaper of
200Mbps (a minimum permitted value) to allow a trickle of necessary
control traffic to get through.

First in patch #1, the QEEC register is extended with fields necessary
to configure the minimum shaper.

In patch #2, minimum shaper is enabled on TCs 8..15.

In patches #3 and #4, first the MC-awareness test is tweaked to support
the minimum shaper, and then a new test is introduced to test that MC
traffic behaves well under UC overload.

Petr Machata (4):
  mlxsw: reg: QEEC: Add minimum shaper fields
  mlxsw: spectrum: Set minimum shaper on MC TCs
  selftests: mlxsw: qos_mc_aware: Tweak for min shaper
  selftests: mlxsw: qos_mc_aware: Add a test for UC awareness

 drivers/net/ethernet/mellanox/mlxsw/reg.h     | 22 ++++-
 .../net/ethernet/mellanox/mlxsw/spectrum.c    | 25 +++++
 .../drivers/net/mlxsw/qos_mc_aware.sh         | 95 ++++++++++++++-----
 3 files changed, 117 insertions(+), 25 deletions(-)

-- 
2.17.2

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2018-11-01  4:56 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-10-31  9:56 [PATCH net 0/4] mlxsw: Enable minimum shaper on MC TCs Ido Schimmel
2018-10-31  9:56 ` [PATCH net 1/4] mlxsw: reg: QEEC: Add minimum shaper fields Ido Schimmel
2018-10-31  9:56 ` [PATCH net 2/4] mlxsw: spectrum: Set minimum shaper on MC TCs Ido Schimmel
2018-10-31  9:56 ` [PATCH net 3/4] selftests: mlxsw: qos_mc_aware: Tweak for min shaper Ido Schimmel
2018-10-31  9:56 ` [PATCH net 4/4] selftests: mlxsw: qos_mc_aware: Add a test for UC awareness Ido Schimmel
2018-10-31 19:57 ` [PATCH net 0/4] mlxsw: Enable minimum shaper on MC TCs David Miller

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