WSL2-Linux-Kernel/net
Kurt Kanzenbach 497cc00224 taprio: Handle short intervals and large packets
When using short intervals e.g. below one millisecond, large packets won't be
transmitted at all. The software implementations checks whether the packet can
be fit into the remaining interval. Therefore, it takes the packet length and
the transmission speed into account. That is correct.

However, for large packets it may be that the transmission time exceeds the
interval resulting in no packet transmission. The same situation works fine with
hardware offloading applied.

The problem has been observed with the following schedule and iperf3:

|tc qdisc replace dev lan1 parent root handle 100 taprio \
|   num_tc 8 \
|   map 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 \
|   queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 \
|   base-time $base \
|   sched-entry S 0x40 500000 \
|   sched-entry S 0xbf 500000 \
|   clockid CLOCK_TAI \
|   flags 0x00

[...]

|root@tsn:~# iperf3 -c 192.168.2.105
|Connecting to host 192.168.2.105, port 5201
|[  5] local 192.168.2.121 port 52610 connected to 192.168.2.105 port 5201
|[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
|[  5]   0.00-1.00   sec  45.2 KBytes   370 Kbits/sec    0   1.41 KBytes
|[  5]   1.00-2.00   sec  0.00 Bytes  0.00 bits/sec    0   1.41 KBytes

After debugging, it seems that the packet length stored in the SKB is about
7000-8000 bytes. Using a 100 Mbit/s link the transmission time is about 600us
which larger than the interval of 500us.

Therefore, segment the SKB into smaller chunks if the packet is too big. This
yields similar results than the hardware offload:

|root@tsn:~# iperf3 -c 192.168.2.105
|Connecting to host 192.168.2.105, port 5201
|- - - - - - - - - - - - - - - - - - - - - - - - -
|[ ID] Interval           Transfer     Bitrate         Retr
|[  5]   0.00-10.00  sec  48.9 MBytes  41.0 Mbits/sec    0             sender
|[  5]   0.00-10.02  sec  48.7 MBytes  40.7 Mbits/sec                  receiver

Furthermore, the segmentation can be skipped for the full offload case, as the
driver or the hardware is expected to handle this.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-03-19 11:32:44 -07:00
..
6lowpan
9p net: 9p: advance iov on empty read 2021-03-03 16:57:59 -08:00
802
8021q vlan/8021q: avoid retpoline overhead on GRO 2021-03-18 19:51:12 -07:00
appletalk appletalk: Fix skb allocation size in loopback case 2021-02-12 16:40:28 -08:00
atm net: atm: pppoatm: use new API for wakeup tasklet 2021-01-29 18:24:05 -08:00
ax25 net: ax25: Fix fall-through warnings for Clang 2021-03-10 12:45:15 -08:00
batman-adv There is only a single patch this time: 2021-03-13 14:27:56 -08:00
bluetooth Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kern 2021-02-11 14:59:01 -08:00
bpf bpf: Add PROG_TEST_RUN support for sk_lookup programs 2021-03-04 19:11:29 -08:00
bpfilter net: remove redundant 'depends on NET' 2021-01-27 17:04:12 -08:00
bridge net: bridge: mcast: factor out common allow/block EHT handling 2021-03-16 11:57:57 -07:00
caif net: caif: Use netif_rx_any_context(). 2021-02-15 13:21:48 -08:00
can net: introduce CAN specific pointer in the struct net_device 2021-02-24 14:32:15 -08:00
ceph libceph: remove osdtimeout option entirely 2021-02-16 12:09:52 +01:00
core /net/core/: fix misspellings using codespell tool 2021-03-18 19:13:41 -07:00
dcb net: dcb: use obj-$(CONFIG_DCB) form in net/Makefile 2021-01-27 17:03:52 -08:00
dccp dccp: Return the correct errno code 2021-02-06 11:15:28 -08:00
decnet decnet: Fix fall-through warnings for Clang 2021-03-10 12:45:15 -08:00
dns_resolver net: remove redundant 'depends on NET' 2021-01-27 17:04:12 -08:00
dsa net: dsa: Add helper to resolve bridge port from DSA port 2021-03-18 16:24:06 -07:00
ethernet ethernet: avoid retpoline overhead on TEB (GENEVE, NvGRE, VxLAN) GRO 2021-03-18 19:51:12 -07:00
ethtool ethtool: Add common function for filling out strings 2021-03-17 11:42:30 -07:00
hsr /net/hsr: fix misspellings using codespell tool 2021-03-18 19:13:41 -07:00
ieee802154
ife net: remove redundant 'depends on NET' 2021-01-27 17:04:12 -08:00
ipv4 net: ipv4: route.c: simplify procfs code 2021-03-16 14:43:49 -07:00
ipv6 seg6: ignore routing header with segments left equal to 0 2021-03-11 16:09:21 -08:00
iucv net/af_iucv: build SG skbs for TRANS_HIPER sockets 2021-01-28 20:36:22 -08:00
kcm net: group skb_shinfo zerocopy related bits together. 2021-01-07 16:08:37 -08:00
key af_key: relax availability checks for skb size calculation 2021-01-04 10:05:50 +01:00
l2tp net: l2tp: reduce log level of messages in receive path, add counter instead 2021-03-03 16:55:02 -08:00
l3mdev net: l3mdev: use obj-$(CONFIG_NET_L3_MASTER_DEV) form in net/Makefile 2021-01-27 17:03:52 -08:00
lapb net: lapb: Copy the skb before sending a packet 2021-02-02 08:40:48 -08:00
llc net: remove redundant 'depends on NET' 2021-01-27 17:04:12 -08:00
mac80211 cfg80211/mac80211: Support disabling HE mode 2021-02-12 09:33:34 +01:00
mac802154
mpls net: avoid infinite loop in mpls_gso_segment when mpls_hlen == 0 2021-03-09 16:12:20 -08:00
mptcp mptcp: remove a list of addrs when flushing 2021-03-12 17:47:45 -08:00
ncsi net/ncsi: Use real net-device for response handler 2020-12-23 12:22:23 -08:00
netfilter netfilter: nftables: bogus check for netlink portID with table owner 2021-03-04 04:02:54 +01:00
netlabel cipso,calipso: resolve a number of problems with the DOI refcounts 2021-03-04 15:26:57 -08:00
netlink mptcp: avoid lock_fast usage in accept path 2021-02-12 16:31:46 -08:00
netrom
nfc TTY/Serial driver changes for 5.12-rc1 2021-02-20 21:28:04 -08:00
nsh
openvswitch openvswitch: Warn over-mtu packets only if iface is UP. 2021-03-16 16:28:30 -07:00
packet net/packet: Improve the comment about LL header visibility criteria 2021-02-06 14:59:28 -08:00
phonet
psample psample: Add additional metadata attributes 2021-03-14 15:00:43 -07:00
qrtr net: qrtr: fix error return code of qrtr_sendmsg() 2021-03-08 15:02:53 -08:00
rds net/rds: Drop duplicate sin and sin6 assignments 2021-03-10 12:45:15 -08:00
rfkill
rose net: rose: Fix fall-through warnings for Clang 2021-03-10 12:45:15 -08:00
rxrpc rxrpc: Fix dependency on IPv6 in udp tunnel config 2021-02-12 16:42:05 -08:00
sched taprio: Handle short intervals and large packets 2021-03-19 11:32:44 -07:00
sctp net: sctp: trivial: fix typo in comment 2021-03-04 13:48:32 -08:00
smc net/smc: use memcpy instead of snprintf to avoid out of bounds read 2021-01-12 20:22:01 -08:00
strparser
sunrpc NFS Client Updates for Linux 5.12 2021-02-26 09:17:24 -08:00
switchdev net: bridge: propagate extack through switchdev_port_attr_set 2021-02-14 17:38:11 -08:00
tipc tipc: remove some unnecessary warnings 2021-03-17 11:51:05 -07:00
tls net/tls: Select SOCK_RX_QUEUE_MAPPING from TLS_DEVICE 2021-02-11 19:08:06 -08:00
unix af_unix: handle idmapped mounts 2021-01-24 14:27:18 +01:00
vmw_vsock vsock: fix locking in vsock_shutdown() 2021-02-09 15:31:22 -08:00
wireless cfg80211/mac80211: Support disabling HE mode 2021-02-12 09:33:34 +01:00
x25 net: x25: Remove unimplemented X.25-over-LLC code stubs 2020-12-12 17:15:33 -08:00
xdp bpf, xdp: Restructure redirect actions 2021-03-10 01:06:34 +01:00
xfrm Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2021-02-09 11:23:41 -08:00
Kconfig bpf: Clean up sockmap related Kconfigs 2021-02-26 12:28:03 -08:00
Makefile net: l3mdev: use obj-$(CONFIG_NET_L3_MASTER_DEV) form in net/Makefile 2021-01-27 17:03:52 -08:00
compat.c
devres.c
socket.c io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
sysctl_net.c