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Eric Dumazet fefa569a9d net_sched: sch_fq: account for schedule/timers drifts
It looks like the following patch can make FQ very precise, even in VM
or stressed hosts. It matters at high pacing rates.

We take into account the difference between the time that was programmed
when last packet was sent, and current time (a drift of tens of usecs is
often observed)

Add an EWMA of the unthrottle latency to help diagnostics.

This latency is the difference between current time and oldest packet in
delayed RB-tree. This accounts for the high resolution timer latency,
but can be different under stress, as fq_check_throttled() can be
opportunistically be called from a dequeue() called after an enqueue()
for a different flow.

Tested:
// Start a 10Gbit flow
$ netperf --google-pacing-rate 1250000000 -H lpaa24 -l 10000 -- -K bbr &

Before patch :
$ sar -n DEV 10 5 | grep eth0 | grep Average
Average:         eth0  17106.04 756876.84   1102.75 1119049.02      0.00      0.00      0.52

After patch :
$ sar -n DEV 10 5 | grep eth0 | grep Average
Average:         eth0  17867.00 800245.90   1151.77 1183172.12      0.00      0.00      0.52

A new iproute2 tc can output the 'unthrottle latency' :

$ tc -s qd sh dev eth0 | grep latency
  0 gc, 0 highprio, 32490767 throttled, 2382 ns latency

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-23 07:19:06 -04:00
..
6lowpan 6lowpan: ndisc: no overreact if no short address is available 2016-09-19 20:19:34 +02:00
9p 9p/trans_virtio: use kvfree() for iov_iter_get_pages_alloc() 2016-08-09 13:42:36 +03:00
802
8021q net: remove type_check from dev_get_nest_level() 2016-08-13 15:15:54 -07:00
appletalk appletalk: use IS_ENABLED() instead of checking for built-in or module 2016-09-10 21:19:10 -07:00
atm lec: use IS_ENABLED() instead of checking for built-in or module 2016-09-10 21:19:10 -07:00
ax25 AX.25: Close socket connection on session completion 2016-06-18 20:55:34 -07:00
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
bluetooth Bluetooth: Set appearance only for LE capable controllers 2016-09-19 21:48:22 +03:00
bridge net: bridge: add helper to call /sbin/bridge-stp 2016-09-13 11:21:31 -04:00
caif caif: Remove unneeded header file 2016-06-28 05:26:14 -04:00
can can: only call can_stat_update with procfs 2016-06-23 11:23:49 +02:00
ceph libceph: using kfree_rcu() to simplify the code 2016-08-08 21:41:42 +02:00
core Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
dcb
dccp Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-07-29 17:38:46 -07:00
decnet net: fix decnet rtnexthop parsing 2016-07-05 14:08:47 -07:00
dns_resolver KEYS: Add a facility to restrict new links into a keyring 2016-04-11 22:37:37 +01:00
dsa net-next: dsa: make the set_addr() operation optional 2016-09-20 04:47:44 -04:00
ethernet
hsr net/hsr: Use setup_timer and mod_timer. 2016-05-16 14:00:43 -04:00
ieee802154 ieee802154: 6lowpan: fix intra pan id check 2016-07-08 13:23:12 +02:00
ipv4 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
ipv6 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
ipx
irda Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
iucv Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-07-29 17:38:46 -07:00
kcm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-12 15:52:44 -07:00
key
l2tp l2tp: constify net_device_ops structures 2016-09-17 10:07:23 -04:00
l3mdev net: ipv6: Remove l3mdev_get_saddr6 2016-09-10 23:12:53 -07:00
lapb net/lapb: tuse %*ph to dump buffers 2016-05-29 22:33:25 -07:00
llc llc: switch type to bool as the timeout is only tested versus 0 2016-09-17 10:05:05 -04:00
mac80211 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
mac802154 mac802154: use rate limited warnings for malformed frames 2016-09-19 20:19:34 +02:00
mpls mpls: get rid of trivial returns 2016-09-01 10:13:15 -07:00
ncsi net/ncsi: avoid maybe-uninitialized warning 2016-07-25 10:32:59 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
netlabel netlabel: Implement CALIPSO config functions for SMACK. 2016-06-27 15:06:18 -04:00
netlink netlink: don't forget to release a rhashtable_iter structure 2016-09-07 17:29:38 -07:00
netrom
nfc NFC: digital: Fix RTOX supervisor PDU handling 2016-07-11 02:02:03 +02:00
openvswitch openvswitch: avoid resetting flow key while installing new flow. 2016-09-20 22:54:35 -04:00
packet Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-07-24 00:53:32 -04:00
phonet
qrtr Merge tag 'qcom-soc-for-4.7-2' into net-next 2016-05-17 14:11:19 -04:00
rds RDS: add __printf format attribute to error reporting functions 2016-08-08 16:16:21 -07:00
rfkill rfkill: Use switch to demux userspace operations 2016-04-05 10:48:53 +02:00
rose rose: limit sk_filter trim to payload 2016-07-13 11:53:40 -07:00
rxrpc rxrpc: Reduce the number of PING ACKs sent 2016-09-22 08:49:22 +01:00
sched net_sched: sch_fq: account for schedule/timers drifts 2016-09-23 07:19:06 -04:00
sctp sctp: fix the handling of SACK Gap Ack blocks 2016-09-23 06:54:58 -04:00
strparser kcm: Remove TCP specific references from kcm and strparser 2016-08-28 23:32:41 -04:00
sunrpc Fix a memory corruption bug that I introduced in 4.7. 2016-09-16 17:00:26 -07:00
switchdev rtnetlink: fdb dump: optimize by saving last interface markers 2016-09-01 16:56:15 -07:00
tipc tipc: fix possible memory leak in tipc_udp_enable() 2016-09-13 11:28:32 -04:00
unix af_unix: split 'u->readlock' into two: 'iolock' and 'bindlock' 2016-09-04 13:29:29 -07:00
vmw_vsock vhost/vsock: drop space available check for TX vq 2016-08-15 05:05:21 +03:00
wimax
wireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
x25 net: x25: remove null checks on arrays calling_ae and called_ae 2016-09-09 18:13:30 -07:00
xfrm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
Kconfig strparser: Stream parser for messages 2016-08-17 19:36:23 -04:00
Makefile strparser: Stream parser for messages 2016-08-17 19:36:23 -04:00
compat.c packet: compat support for sock_fprog 2016-06-09 23:41:03 -07:00
socket.c fs: poll/select/recvmmsg: use timespec64 for timeout events 2016-05-19 19:12:14 -07:00
sysctl_net.c net: make net namespace sysctls belong to container's owner 2016-08-14 21:08:58 -07:00