linux-toradex.git/net/sched/Makefile, branch v3.4

net/sched: sch_plug - Queue traffic until an explicit release command

2012-02-07T17:54:56+00:00

The qdisc supports two operations - plug and unplug. When the
qdisc receives a plug command via netlink request, packets arriving
henceforth are buffered until a corresponding unplug command is received.
Depending on the type of unplug command, the queue can be unplugged
indefinitely or selectively.

This qdisc can be used to implement output buffering, an essential
functionality required for consistent recovery in checkpoint based
fault-tolerance systems. Output buffering enables speculative execution
by allowing generated network traffic to be rolled back. It is used to
provide network protection for Xen Guests in the Remus high availability
project, available as part of Xen.

This module is generic enough to be used by any other system that wishes
to add speculative execution and output buffering to its applications.

This module was originally available in the linux 2.6.32 PV-OPS tree,
used as dom0 for Xen.

For more information, please refer to http://nss.cs.ubc.ca/remus/
and http://wiki.xensource.com/xenwiki/Remus

Changes in V3:
  * Removed debug output (printk) on queue overflow
  * Added TCQ_PLUG_RELEASE_INDEFINITE - that allows the user to
    use this qdisc, for simple plug/unplug operations.
  * Use of packet counts instead of pointers to keep track of
    the buffers in the queue.

Signed-off-by: Shriram Rajagopalan 
Signed-off-by: Brendan Cully 
[author of the code in the linux 2.6.32 pvops tree]
Signed-off-by: David S. Miller

pkt_sched: QFQ - quick fair queue scheduler

2011-04-04T18:10:24+00:00

This is an implementation of the Quick Fair Queue scheduler developed
by Fabio Checconi. The same algorithm is already implemented in ipfw
in FreeBSD. Fabio had an earlier version developed on Linux, I just
cleaned it up.  Thanks to Eric Dumazet for testing this under load.

Signed-off-by: Stephen Hemminger 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net_sched: SFB flow scheduler

2011-02-23T22:05:11+00:00

This is the Stochastic Fair Blue scheduler, based on work from :

W. Feng, D. Kandlur, D. Saha, K. Shin. Blue: A New Class of Active Queue
Management Algorithms. U. Michigan CSE-TR-387-99, April 1999.

http://www.thefengs.com/wuchang/blue/CSE-TR-387-99.pdf

This implementation is based on work done by Juliusz Chroboczek

General SFB algorithm can be found in figure 14, page 15:

B[l][n] : L x N array of bins (L levels, N bins per level)
enqueue()
Calculate hash function values h{0}, h{1}, .. h{L-1}
Update bins at each level
for i = 0 to L - 1
   if (B[i][h{i}].qlen > bin_size)
      B[i][h{i}].p_mark += p_increment;
   else if (B[i][h{i}].qlen == 0)
      B[i][h{i}].p_mark -= p_decrement;
p_min = min(B[0][h{0}].p_mark ... B[L-1][h{L-1}].p_mark);
if (p_min == 1.0)
    ratelimit();
else
    mark/drop with probabilty p_min;

I did the adaptation of Juliusz code to meet current kernel standards,
and various changes to address previous comments :

http://thread.gmane.org/gmane.linux.network/90225
http://thread.gmane.org/gmane.linux.network/90375

Default flow classifier is the rxhash introduced by RPS in 2.6.35, but
we can use an external flow classifier if wanted.

tc qdisc add dev $DEV parent 1:11 handle 11:  \
        est 0.5sec 2sec sfb limit 128

tc filter add dev $DEV protocol ip parent 11: handle 3 \
        flow hash keys dst divisor 1024

Notes:

1) SFB default child qdisc is pfifo_fast. It can be changed by another
qdisc but a child qdisc MUST not drop a packet previously queued. This
is because SFB needs to handle a dequeued packet in order to maintain
its virtual queue states. pfifo_head_drop or CHOKe should not be used.

2) ECN is enabled by default, unlike RED/CHOKe/GRED

With help from Patrick McHardy & Andi Kleen

Signed-off-by: Eric Dumazet 
CC: Juliusz Chroboczek 
CC: Stephen Hemminger 
CC: Patrick McHardy 
CC: Andi Kleen 
CC: John W. Linville 
Signed-off-by: David S. Miller

sched: CHOKe flow scheduler

2011-02-03T04:52:42+00:00

CHOKe ("CHOose and Kill" or "CHOose and Keep") is an alternative
packet scheduler based on the Random Exponential Drop (RED) algorithm.

The core idea is:
  For every packet arrival:
  	Calculate Qave
	if (Qave < minth)
	     Queue the new packet
	else
	     Select randomly a packet from the queue
	     if (both packets from same flow)
	     then Drop both the packets
	     else if (Qave > maxth)
	          Drop packet
	     else
	       	  Admit packet with proability p (same as RED)

See also:
  Rong Pan, Balaji Prabhakar, Konstantinos Psounis, "CHOKe: a stateless active
   queue management scheme for approximating fair bandwidth allocation",
  Proceeding of INFOCOM'2000, March 2000.

Help from:
     Eric Dumazet 
     Patrick McHardy 

Signed-off-by: Stephen Hemminger 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net_sched: implement a root container qdisc sch_mqprio

2011-01-20T07:31:11+00:00

This implements a mqprio queueing discipline that by default creates
a pfifo_fast qdisc per tx queue and provides the needed configuration
interface.

Using the mqprio qdisc the number of tcs currently in use along
with the range of queues alloted to each class can be configured. By
default skbs are mapped to traffic classes using the skb priority.
This mapping is configurable.

Configurable parameters,

struct tc_mqprio_qopt {
	__u8    num_tc;
	__u8    prio_tc_map[TC_BITMASK + 1];
	__u8    hw;
	__u16   count[TC_MAX_QUEUE];
	__u16   offset[TC_MAX_QUEUE];
};

Here the count/offset pairing give the queue alignment and the
prio_tc_map gives the mapping from skb->priority to tc.

The hw bit determines if the hardware should configure the count
and offset values. If the hardware bit is set then the operation
will fail if the hardware does not implement the ndo_setup_tc
operation. This is to avoid undetermined states where the hardware
may or may not control the queue mapping. Also minimal bounds
checking is done on the count/offset to verify a queue does not
exceed num_tx_queues and that queue ranges do not overlap. Otherwise
it is left to user policy or hardware configuration to create
useful mappings.

It is expected that hardware QOS schemes can be implemented by
creating appropriate mappings of queues in ndo_tc_setup().

One expected use case is drivers will use the ndo_setup_tc to map
queue ranges onto 802.1Q traffic classes. This provides a generic
mechanism to map network traffic onto these traffic classes and
removes the need for lower layer drivers to know specifics about
traffic types.

Signed-off-by: John Fastabend 
Signed-off-by: David S. Miller

net/sched: add ACT_CSUM action to update packets checksums

2010-08-20T08:42:59+00:00

net/sched: add ACT_CSUM action to update packets checksums

ACT_CSUM can be called just after ACT_PEDIT in order to re-compute some
altered checksums in IPv4 and IPv6 packets. The following checksums are
supported by this patch:
 - IPv4: IPv4 header, ICMP, IGMP, TCP, UDP & UDPLite
 - IPv6: ICMPv6, TCP, UDP & UDPLite
It's possible to request in the same action to update different kind of
checksums, if the packets flow mix TCP, UDP and UDPLite, ...

An example of usage is done in the associated iproute2 patch.

Version 3 changes:
 - remove useless goto instructions
 - improve IPv6 hop options decoding

Version 2 changes:
 - coding style correction
 - remove useless arguments of some functions
 - use stack in tcf_csum_dump()
 - add tcf_csum_skb_nextlayer() to factor code

Signed-off-by: Gregoire Baron 
Acked-by: jamal 
Signed-off-by: David S. Miller

net_sched: add classful multiqueue dummy scheduler

2009-09-06T09:07:05+00:00

This patch adds a classful dummy scheduler which can be used as root qdisc
for multiqueue devices and exposes each device queue as a child class.

This allows to address queues individually and graft them similar to regular
classes. Additionally it presents an accumulated view of the statistics of
all real root qdiscs in the dummy root.

Two new callbacks are added to the qdisc_ops and qdisc_class_ops:

- cl_ops->select_queue selects the tx queue number for new child classes.

- qdisc_ops->attach() overrides root qdisc device grafting to attach
  non-shared qdiscs to the queues.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

pkt_sched: add DRR scheduler

2008-11-20T12:10:00+00:00

Add classful DRR scheduler as a more flexible replacement for SFQ.

The main difference to the algorithm described in "Efficient Fair Queueing
using Deficit Round Robin" is that this implementation doesn't drop packets
from the longest queue on overrun because its classful and limits are
handled by each individual child qdisc.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

pkt_sched: Control group classifier

2008-11-08T06:56:00+00:00

The classifier should cover the most common use case and will work
without any special configuration.

The principle of the classifier is to directly access the
task_struct via get_current(). In order for this to work,
classification requests from softirqs must be ignored. This is
not a problem because the vast majority of packets in softirq
context are not assigned to a task anyway. For this to work, a
mechanism is needed to trace softirq context. 

This repost goes back to the method of relying on the number of
nested bh disable calls for the sake of not adding too much
complexity and the option to come up with something more reliable
if actually needed.

Signed-off-by: Thomas Graf 
Signed-off-by: David S. Miller

pkt_action: add new action skbedit

2008-09-12T23:30:20+00:00

This new action will have the ability to change the priority and/or
queue_mapping fields on an sk_buff.

Signed-off-by: Alexander Duyck 
Signed-off-by: Jeff Kirsher 
Signed-off-by: David S. Miller