BMC/Intel-BMC/linux.git/net/sched/sch_netem.c, branch dev

net: sched: deprecate enqueue_root()

2015-05-11T18:17:32+00:00

Only left enqueue_root() user is netem, and it looks not necessary : qdisc_skb_cb(skb)->pkt_len is preserved after one skb_clone() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

netem: Fixes byte backlog accounting for the first of two chained netem instances

2015-04-07T22:34:24+00:00

Fixes byte backlog accounting for the first of two chained netem instances. Bytes backlog reported now corresponds to the number of queued packets. When two netem instances are chained, for instance to apply rate and queue limitation followed by packet delay, the number of backlogged bytes reported by the first netem instance is wrong. It reports the sum of bytes in the queues of the first and second netem. The first netem reports the correct number of backlogged packets but not bytes. This is shown in the example below. Consider a chain of two netem schedulers created using the following commands: $ tc -s qdisc replace dev veth2 root handle 1:0 netem rate 10000kbit limit 100 $ tc -s qdisc add dev veth2 parent 1:0 handle 2: netem delay 50ms Start an iperf session to send packets out on the specified interface and monitor the backlog using tc: $ tc -s qdisc show dev veth2 Output using unpatched netem: qdisc netem 1: root refcnt 2 limit 100 rate 10000Kbit Sent 98422639 bytes 65434 pkt (dropped 123, overlimits 0 requeues 0) backlog 172694b 73p requeues 0 qdisc netem 2: parent 1: limit 1000 delay 50.0ms Sent 98422639 bytes 65434 pkt (dropped 0, overlimits 0 requeues 0) backlog 63588b 42p requeues 0 The interface used to produce this output has an MTU of 1500. The output for backlogged bytes behind netem 1 is 172694b. This value is not correct. Consider the total number of sent bytes and packets. By dividing the number of sent bytes by the number of sent packets, we get an average packet size of ~=1504. If we divide the number of backlogged bytes by packets, we get ~=2365. This is due to the first netem incorrectly counting the 63588b which are in netem 2's queue as being in its own queue. To verify this is the case, we subtract them from the reported value and divide by the number of packets as follows: 172694 - 63588 = 109106 bytes actualled backlogged in netem 1 109106 / 73 packets ~= 1494 bytes (which matches our MTU) The root cause is that the byte accounting is not done at the same time with packet accounting. The solution is to update the backlog value every time the packet queue is updated. Signed-off-by: Joseph D Beshay Acked-by: Hagen Paul Pfeifer Signed-off-by: David S. Miller

net: add rbnode to struct sk_buff

2014-11-03T21:13:03+00:00

Yaogong replaces TCP out of order receive queue by an RB tree. As netem already does a private skb->{next/prev/tstamp} union with a 'struct rb_node', lets do this in a cleaner way. Signed-off-by: Eric Dumazet Cc: Yaogong Wang Signed-off-by: David S. Miller

net: sched: implement qstat helper routines

2014-09-30T05:02:26+00:00

This adds helpers to manipulate qstats logic and replaces locations that touch the counters directly. This simplifies future patches to push qstats onto per cpu counters. Signed-off-by: John Fastabend Signed-off-by: David S. Miller

net: use the new API kvfree()

2014-06-05T07:49:51+00:00

It is available since v3.15-rc5. Cc: Pablo Neira Ayuso Cc: "David S. Miller" Signed-off-by: Cong Wang Signed-off-by: David S. Miller

sch_netem: replace magic numbers with enumerate in get_loss_clg

2014-02-17T21:55:54+00:00

Replace two magic numbers which intialize clgstate::state. Signed-off-by: Yang Yingliang Signed-off-by: David S. Miller

sch_netem: replace magic numbers with enumerate in GE model

2014-02-14T05:15:20+00:00

Replace some magic numbers which describe states of GE model loss generator with enumerate. Signed-off-by: Yang Yingliang Signed-off-by: David S. Miller

sch_netem: change some func's param from "struct Qdisc " to "struct netem_sched_data "

2014-02-14T05:15:20+00:00

In netem_change(), we have already get "struct netem_sched_data *q". Replace params of get_correlation() and other similar functions with "struct netem_sched_data *q". Signed-off-by: Yang Yingliang Signed-off-by: David S. Miller

sch_netem: return errcode before setting params

2014-02-14T05:15:20+00:00

get_dist_table() and get_loss_clg() may be failed. These two functions should be called after setting the members of qdisc_priv(sch), or it will break the old settings while either of them is failed. Signed-off-by: Yang Yingliang Signed-off-by: David S. Miller

reciprocal_divide: update/correction of the algorithm

2014-01-22T07:17:20+00:00

Jakub Zawadzki noticed that some divisions by reciprocal_divide() were not correct [1][2], which he could also show with BPF code after divisions are transformed into reciprocal_value() for runtime invariance which can be passed to reciprocal_divide() later on; reverse in BPF dump ended up with a different, off-by-one K in some situations. This has been fixed by Eric Dumazet in commit aee636c4809fa5 ("bpf: do not use reciprocal divide"). This follow-up patch improves reciprocal_value() and reciprocal_divide() to work in all cases by using Granlund and Montgomery method, so that also future use is safe and without any non-obvious side-effects. Known problems with the old implementation were that division by 1 always returned 0 and some off-by-ones when the dividend and divisor where very large. This seemed to not be problematic with its current users, as far as we can tell. Eric Dumazet checked for the slab usage, we cannot surely say so in the case of flex_array. Still, in order to fix that, we propose an extension from the original implementation from commit 6a2d7a955d8d resp. [3][4], by using the algorithm proposed in "Division by Invariant Integers Using Multiplication" [5], Torbjörn Granlund and Peter L. Montgomery, that is, pseudocode for q = n/d where q, n, d is in u32 universe: 1) Initialization: int l = ceil(log_2 d) uword m' = floor((1<<32)*((1<>32 q = (t+((n-t)>>sh_1))>>sh_2 The assembler implementation from Agner Fog [6] also helped a lot while implementing. We have tested the implementation on x86_64, ppc64, i686, s390x; on x86_64/haswell we're still half the latency compared to normal divide. Joint work with Daniel Borkmann. [1] http://www.wireshark.org/~darkjames/reciprocal-buggy.c [2] http://www.wireshark.org/~darkjames/set-and-dump-filter-k-bug.c [3] https://gmplib.org/~tege/division-paper.pdf [4] http://homepage.cs.uiowa.edu/~jones/bcd/divide.html [5] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1.2556 [6] http://www.agner.org/optimize/asmlib.zip Reported-by: Jakub Zawadzki Cc: Eric Dumazet Cc: Austin S Hemmelgarn Cc: linux-kernel@vger.kernel.org Cc: Jesse Gross Cc: Jamal Hadi Salim Cc: Stephen Hemminger Cc: Matt Mackall Cc: Pekka Enberg Cc: Christoph Lameter Cc: Andy Gospodarek Cc: Veaceslav Falico Cc: Jay Vosburgh Cc: Jakub Zawadzki Signed-off-by: Daniel Borkmann Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller

BMC/Intel-BMC/linux.git/net/sched/sch_netem.c, branch dev

net: sched: deprecate enqueue_root()

netem: Fixes byte backlog accounting for the first of two chained netem instances

net: add rbnode to struct sk_buff

net: sched: implement qstat helper routines

net: use the new API kvfree()

sch_netem: replace magic numbers with enumerate in get_loss_clg

sch_netem: replace magic numbers with enumerate in GE model

sch_netem: change some func's param from "struct Qdisc *" to "struct netem_sched_data *"

sch_netem: return errcode before setting params

reciprocal_divide: update/correction of the algorithm

sch_netem: change some func's param from "struct Qdisc " to "struct netem_sched_data "