linux/net
Vimalkumar 56b765b79e htb: improved accuracy at high rates
Current HTB (and TBF) uses rate table computed by the "tc"
userspace program, which has the following issue:

The rate table has 256 entries to map packet lengths
to token (time units).  With TSO sized packets, the
256 entry granularity leads to loss/gain of rate,
making the token bucket inaccurate.

Thus, instead of relying on rate table, this patch
explicitly computes the time and accounts for packet
transmission times with nanosecond granularity.

This greatly improves accuracy of HTB with a wide
range of packet sizes.

Example:

tc qdisc add dev $dev root handle 1: \
        htb default 1

tc class add dev $dev classid 1:1 parent 1: \
        rate 5Gbit mtu 64k

Here is an example of inaccuracy:

$ iperf -c host -t 10 -i 1

With old htb:
eth4:   34.76 Mb/s In  5827.98 Mb/s Out -  65836.0 p/s In  481273.0 p/s Out
[SUM]  9.0-10.0 sec   669 MBytes  5.61 Gbits/sec
[SUM]  0.0-10.0 sec  6.50 GBytes  5.58 Gbits/sec

With new htb:
eth4:   28.36 Mb/s In  5208.06 Mb/s Out -  53704.0 p/s In  430076.0 p/s Out
[SUM]  9.0-10.0 sec   594 MBytes  4.98 Gbits/sec
[SUM]  0.0-10.0 sec  5.80 GBytes  4.98 Gbits/sec

The bits per second on the wire is still 5200Mb/s with new HTB
because qdisc accounts for packet length using skb->len, which
is smaller than total bytes on the wire if GSO is used.  But
that is for another patch regardless of how time is accounted.

Many thanks to Eric Dumazet for review and feedback.

Signed-off-by: Vimalkumar <j.vimal@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-11-03 15:24:01 -04:00
..
9p The following changes since commit 4cbe5a555f: 2012-10-12 09:59:23 +09:00
802
8021q vlan: use IS_ENABLED() 2012-11-01 12:41:35 -04:00
appletalk userns: Print out socket uids in a user namespace aware fashion. 2012-08-14 21:48:06 -07:00
atm net🏧fix up ENOIOCTLCMD error handling 2012-08-31 16:14:33 -04:00
ax25 userns: Convert net/ax25 to use kuid_t where appropriate 2012-08-14 21:49:42 -07:00
batman-adv batman-adv: add kernel-doc for enum batadv_dbg_level 2012-10-29 09:42:51 +01:00
bluetooth userns: Properly print bluetooth socket uids 2012-10-12 13:16:47 -07:00
bridge eth: Rename and properly align br_reserved_address array 2012-11-02 21:34:05 -04:00
caif caif: move the dereference below the NULL test 2012-09-10 16:13:31 -04:00
can sections: fix section conflicts in net/can 2012-10-06 03:04:45 +09:00
ceph Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-14 13:39:34 -07:00
core pktgen: clean up ktime_t helpers 2012-11-03 14:50:15 -04:00
dcb netlink: Rename pid to portid to avoid confusion 2012-09-10 15:30:41 -04:00
dccp tcp: better retrans tracking for defer-accept 2012-11-03 14:45:00 -04:00
decnet sections: fix section conflicts in net 2012-10-06 03:04:45 +09:00
dns_resolver Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-14 13:39:34 -07:00
dsa workqueue: deprecate flush[_delayed]_work_sync() 2012-08-20 14:51:24 -07:00
ethernet ipx: move peII functions 2012-07-19 10:48:00 -07:00
ieee802154 net/ieee802154/6lowpan.c: Remove unecessary semicolon 2012-09-18 16:08:19 -04:00
ipv4 tcp: better retrans tracking for defer-accept 2012-11-03 14:45:00 -04:00
ipv6 ipv6: introduce ip6_rt_put() 2012-11-03 14:59:05 -04:00
ipx userns: Print out socket uids in a user namespace aware fashion. 2012-08-14 21:48:06 -07:00
irda silence some noisy printks in irda 2012-10-04 15:53:48 -04:00
iucv net: remove skb_orphan_try() 2012-06-15 15:30:15 -07:00
key net/key/af_key.c: add range checks on ->sadb_x_policy_len 2012-10-01 17:15:06 -04:00
l2tp l2tp: session is an array not a pointer 2012-10-26 03:46:41 -04:00
lapb
llc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-10-02 11:11:09 -07:00
mac80211 mac80211: use ieee80211_free_txskb to fix possible skb leaks 2012-10-08 15:06:05 -04:00
mac802154 mac802154: sparse warnings: make symbols static 2012-07-12 07:54:45 -07:00
netfilter Merge branch 'master' of git://1984.lsi.us.es/nf-next 2012-10-26 14:40:55 -04:00
netlabel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-10-02 13:38:27 -07:00
netlink netlink: use kfree_rcu() in netlink_release() 2012-10-18 15:34:30 -04:00
netrom net: change return values from -EACCES to -EPERM 2012-09-21 13:58:08 -04:00
nfc Remove noisy printks from llcp_sock_connect 2012-10-04 15:58:47 -04:00
openvswitch net/openvswitch/vport.c: Remove unecessary semicolon 2012-09-18 16:08:19 -04:00
packet packet: minor: remove unused err assignment 2012-10-26 02:17:20 -04:00
phonet netlink: Rename pid to portid to avoid confusion 2012-09-10 15:30:41 -04:00
rds RDS: fix rds-ping spinlock recursion 2012-10-09 13:57:23 -04:00
rfkill Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-10-02 13:38:27 -07:00
rose
rxrpc Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-14 13:39:34 -07:00
sched htb: improved accuracy at high rates 2012-11-03 15:24:01 -04:00
sctp sctp: Clean up type-punning in sctp_cmd_t union 2012-11-03 14:54:55 -04:00
sunrpc Merge branch 'for-3.7' of git://linux-nfs.org/~bfields/linux 2012-10-13 10:53:54 +09:00
tipc tipc: prevent dropped connections due to rcvbuf overflow 2012-10-04 15:53:48 -04:00
unix sock-diag: Report shutdown for inet and unix sockets (v2) 2012-10-23 14:57:52 -04:00
wanrouter wanmain: comparing array with NULL 2012-07-24 13:55:21 -07:00
wimax
wireless Merge branch 'for-davem' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next 2012-09-30 02:30:16 -04:00
x25 net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
xfrm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-10-02 13:38:27 -07:00
compat.c make get_file() return its argument 2012-09-26 21:10:25 -04:00
Kconfig net: Add INET dependency on aes crypto for the sake of TCP fastopen. 2012-09-04 14:20:14 -04:00
Makefile
nonet.c
socket.c cgroup: net_cls: Rework update socket logic 2012-10-26 03:40:51 -04:00
sysctl_net.c