linux_dsm_epyc7002/net
Eric Dumazet 051ba67447 tcp: force a PSH flag on TSO packets
When tcp sends a TSO packet, adding a PSH flag on it
reduces the sojourn time of GRO packet in GRO receivers.

This is particularly the case under pressure, since RX queues
receive packets for many concurrent flows.

A sender can give a hint to GRO engines when it is
appropriate to flush a super-packet, especially when pacing
is in the picture, since next packet is probably delayed by
one ms.

Having less packets in GRO engine reduces chance
of LRU eviction or inflated RTT, and reduces GRO cost.

We found recently that we must not set the PSH flag on
individual full-size MSS segments [1] :

 Under pressure (CWR state), we better let the packet sit
 for a small delay (depending on NAPI logic) so that the
 ACK packet is delayed, and thus next packet we send is
 also delayed a bit. Eventually the bottleneck queue can
 be drained. DCTCP flows with CWND=1 have demonstrated
 the issue.

This patch allows to slowdown the aggregate traffic without
involving high resolution timers on senders and/or
receivers.

It has been used at Google for about four years,
and has been discussed at various networking conferences.

[1] segments smaller than MSS already have PSH flag set
    by tcp_sendmsg() / tcp_mark_push(), unless MSG_MORE
    has been requested by the user.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-09-11 23:59:01 +01:00
..
6lowpan 6lowpan: no need to check return value of debugfs_create functions 2019-07-06 12:50:01 +02:00
9p 9p pull request for inclusion in 5.13 2019-07-12 17:31:19 -07:00
802 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
8021q Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-22 08:59:24 -04:00
appletalk net: Use skb_frag_off accessors 2019-07-30 14:21:32 -07:00
atm pppoatm: use %*ph to print small buffer 2019-09-05 12:33:28 +02:00
ax25 ax25: fix inconsistent lock state in ax25_destroy_timer 2019-06-16 14:22:37 -07:00
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
bluetooth Bluetooth: hidp: Fix assumptions on the return value of hidp_send_message 2019-09-06 15:55:40 +02:00
bpf bpf/flow_dissector: support flags in BPF_PROG_TEST_RUN 2019-07-25 18:00:41 -07:00
bpfilter Kbuild updates for v5.3 2019-07-12 16:03:16 -07:00
bridge Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
caif treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
can can: add support of SAE J1939 protocol 2019-09-04 14:22:33 +02:00
ceph libceph: don't call crypto_free_sync_skcipher() on a NULL tfm 2019-08-28 12:33:46 +02:00
core devlink: add 'reset_dev_on_drv_probe' param 2019-09-10 17:29:26 +01:00
dcb treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 201 2019-05-30 11:29:52 -07:00
dccp proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
decnet treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 53 2019-05-24 17:36:42 +02:00
dns_resolver Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
dsa net: dsa: Fix off-by-one number of calls to devlink_port_unregister 2019-09-02 11:59:29 -07:00
ethernet Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-07 11:00:14 -07:00
hsr hsr: switch ->dellink() to ->ndo_uninit() 2019-07-11 14:37:45 -07:00
ieee802154 Merge branch 'ieee802154-for-davem-2019-08-24' of git://git.kernel.org/pub/scm/linux/kernel/git/sschmidt/wpan 2019-08-24 13:46:57 -07:00
ife treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
ipv4 tcp: force a PSH flag on TSO packets 2019-09-11 23:59:01 +01:00
ipv6 ipv6: Don't use dst gateway directly in ip6_confirm_neigh() 2019-09-11 23:52:17 +01:00
iucv net/af_iucv: mark expected switch fall-throughs 2019-07-29 10:26:14 -07:00
kcm net: Use skb_frag_off accessors 2019-07-30 14:21:32 -07:00
key Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-07-08 19:48:57 -07:00
l2tp compat_ioctl: pppoe: fix PPPOEIOCSFWD handling 2019-07-30 14:42:13 -07:00
l3mdev ipv6: convert major tx path to use RT6_LOOKUP_F_DST_NOREF 2019-06-23 13:24:17 -07:00
lapb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-17 20:20:36 -07:00
llc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 281 2019-06-05 17:36:36 +02:00
mac80211 We have a number of changes, but things are settling down: 2019-09-11 14:57:17 +01:00
mac802154 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
mpls ipv4: mpls: fix mpls_xmit for iptunnel 2019-08-25 14:34:08 -07:00
ncsi net/ncsi: add response handlers for PLDM over NC-SI 2019-08-31 23:54:03 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2019-09-07 16:31:30 +02:00
netlabel netlabel: remove redundant assignment to pointer iter 2019-09-01 11:45:02 -07:00
netlink net: remove empty netlink_tap_exit_net 2019-06-14 19:50:33 -07:00
netrom netrom: hold sock when setting skb->destructor 2019-07-24 15:49:05 -07:00
nfc NFC: fix attrs checks in netlink interface 2019-07-29 08:56:26 -07:00
nsh treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
openvswitch net: openvswitch: Set OvS recirc_id from tc chain index 2019-09-06 14:59:18 +02:00
packet net/packet: fix race in tpacket_snd() 2019-08-15 13:59:48 -07:00
phonet treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 336 2019-06-05 17:37:07 +02:00
psample net: sched: act_sample: fix psample group handling on overwrite 2019-08-28 15:53:51 -07:00
qrtr treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 284 2019-06-05 17:36:37 +02:00
rds Convert usage of IN_MULTICAST to ipv4_is_multicast 2019-09-05 09:38:32 +02:00
rfkill treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rose treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
sched net_sched: act_police: add 2 new attributes to support police 64bit rate and peakrate 2019-09-06 15:02:16 +02:00
sctp sctp: allow users to set ep ecn flag by sockopt 2019-08-27 20:54:14 -07:00
smc net/smc: make sure EPOLLOUT is raised 2019-08-20 12:25:14 -07:00
strparser Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-22 08:59:24 -04:00
sunrpc sunrpc: Use kzfree rather than its implementation. 2019-09-05 12:06:04 +02:00
switchdev treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-19 11:54:03 -07:00
tls net/tls: align non temporal copy to cache lines 2019-09-07 18:10:34 +02:00
unix Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-07 11:00:14 -07:00
vmw_vsock vsock/virtio: a better comment on credit update 2019-09-05 09:53:01 +02:00
wimax wimax: no need to check return value of debugfs_create functions 2019-08-10 15:25:47 -07:00
wireless We have a number of changes, but things are settling down: 2019-09-11 14:57:17 +01:00
x25 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00
xdp Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-09-06 16:49:17 +02:00
xfrm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-27 14:23:31 -07:00
compat.c uio: make import_iovec()/compat_import_iovec() return bytes on success 2019-05-31 15:30:03 -06:00
Kconfig devlink: Add packet trap infrastructure 2019-08-17 12:40:08 -07:00
Makefile net: split out functions related to registering inflight socket files 2019-02-28 08:24:23 -07:00
socket.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
sysctl_net.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00