linux_dsm_epyc7002/net/dsa
Alexander Lobakin e131a56348 net: dsa: add GRO support via gro_cells
gro_cells lib is used by different encapsulating netdevices, such as
geneve, macsec, vxlan etc. to speed up decapsulated traffic processing.
CPU tag is a sort of "encapsulation", and we can use the same mechs to
greatly improve overall DSA performance.
skbs are passed to the GRO layer after removing CPU tags, so we don't
need any new packet offload types as it was firstly proposed by me in
the first GRO-over-DSA variant [1].

The size of struct gro_cells is sizeof(void *), so hot struct
dsa_slave_priv becomes only 4/8 bytes bigger, and all critical fields
remain in one 32-byte cacheline.
The other positive side effect is that drivers for network devices
that can be shipped as CPU ports of DSA-driven switches can now use
napi_gro_frags() to pass skbs to kernel. Packets built that way are
completely non-linear and are likely being dropped without GRO.

This was tested on to-be-mainlined-soon Ethernet driver that uses
napi_gro_frags(), and the overall performance was on par with the
variant from [1], sometimes even better due to minimal overhead.
net.core.gro_normal_batch tuning may help to push it to the limit
on particular setups and platforms.

iperf3 IPoE VLAN NAT TCP forwarding (port1.218 -> port0) setup
on 1.2 GHz MIPS board:

5.7-rc2 baseline:

[ID]  Interval         Transfer     Bitrate        Retr
[ 5]  0.00-120.01 sec  9.00 GBytes  644 Mbits/sec  413  sender
[ 5]  0.00-120.00 sec  8.99 GBytes  644 Mbits/sec       receiver

Iface      RX packets  TX packets
eth0       7097731     7097702
port0      426050      6671829
port1      6671681     425862
port1.218  6671677     425851

With this patch:

[ID]  Interval         Transfer     Bitrate        Retr
[ 5]  0.00-120.01 sec  12.2 GBytes  870 Mbits/sec  122  sender
[ 5]  0.00-120.00 sec  12.2 GBytes  870 Mbits/sec       receiver

Iface      RX packets  TX packets
eth0       9474792     9474777
port0      455200      353288
port1      9019592     455035
port1.218  353144      455024

v2:
 - Add some performance examples in the commit message;
 - No functional changes.

[1] https://lore.kernel.org/netdev/20191230143028.27313-1-alobakin@dlink.ru/

Signed-off-by: Alexander Lobakin <bloodyreaper@yandex.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-04-23 12:32:13 -07:00
..
dsa2.c net: dsa: implement auto-normalization of MTU for bridge hardware datapath 2020-03-27 16:07:25 -07:00
dsa_priv.h net: dsa: add GRO support via gro_cells 2020-04-23 12:32:13 -07:00
dsa.c net: dsa: add GRO support via gro_cells 2020-04-23 12:32:13 -07:00
Kconfig net: dsa: add GRO support via gro_cells 2020-04-23 12:32:13 -07:00
Makefile net: dsa: add support for Atheros AR9331 TAG format 2019-12-20 17:05:47 -08:00
master.c net: dsa: configure the MTU for switch ports 2020-03-27 16:07:24 -07:00
port.c net: dsa: Down cpu/dsa ports phylink will control 2020-04-14 16:33:26 -07:00
slave.c net: dsa: add GRO support via gro_cells 2020-04-23 12:32:13 -07:00
switch.c net: dsa: configure the MTU for switch ports 2020-03-27 16:07:24 -07:00
tag_8021q.c net: dsa: tag_8021q: replace dsa_8021q_remove_header with __skb_vlan_pop 2020-03-24 16:19:01 -07:00
tag_ar9331.c net: dsa: tag_ar9331: Make sure there is headroom for tag 2020-02-14 07:34:51 -08:00
tag_brcm.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-25 18:58:11 -07:00
tag_dsa.c dsa: Cleanup unneeded table and make tag structures static 2019-04-28 19:41:01 -04:00
tag_edsa.c dsa: Cleanup unneeded table and make tag structures static 2019-04-28 19:41:01 -04:00
tag_gswip.c net: dsa: tag_gswip: fix typo in tagger name 2020-01-16 13:58:26 +01:00
tag_ksz.c net: dsa: ksz: use common define for tag len 2019-12-20 21:06:49 -08:00
tag_lan9303.c dsa: Cleanup unneeded table and make tag structures static 2019-04-28 19:41:01 -04:00
tag_mtk.c dsa: Cleanup unneeded table and make tag structures static 2019-04-28 19:41:01 -04:00
tag_ocelot.c net: mscc: ocelot: eliminate confusion between CPU and NPI port 2020-03-04 14:19:00 -08:00
tag_qca.c net: dsa: tag_qca: Make sure there is headroom for tag 2020-02-14 07:34:51 -08:00
tag_sja1105.c net: dsa: tag_8021q: replace dsa_8021q_remove_header with __skb_vlan_pop 2020-03-24 16:19:01 -07:00
tag_trailer.c dsa: Cleanup unneeded table and make tag structures static 2019-04-28 19:41:01 -04:00