A Discrete-Event Network Simulator
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codel-queue-disc.h
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1/*
2 * Copyright (c) 2012 Andrew McGregor
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation;
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16 *
17 * Codel, the COntrolled DELay Queueing discipline
18 * Based on ns2 simulation code presented by Kathie Nichols
19 *
20 * This port based on linux kernel code by
21 * Authors:
22 * Dave Täht <d@taht.net>
23 * Eric Dumazet <edumazet@google.com>
24 *
25 * Ported to ns-3 by: Andrew McGregor <andrewmcgr@gmail.com>
26 */
27
28#ifndef CODEL_H
29#define CODEL_H
30
31#include "queue-disc.h"
32
33#include "ns3/nstime.h"
34#include "ns3/simulator.h"
35#include "ns3/string.h"
36#include "ns3/trace-source-accessor.h"
37#include "ns3/traced-value.h"
38
39class CoDelQueueDiscNewtonStepTest; // Forward declaration for unit test
40class CoDelQueueDiscControlLawTest; // Forward declaration for unit test
41
42namespace ns3
43{
44
49static const int CODEL_SHIFT = 10;
50
51#define DEFAULT_CODEL_LIMIT 1000
52#define REC_INV_SQRT_BITS (8 * sizeof(uint16_t))
53#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
54
55class TraceContainer;
56
64{
65 public:
71 static TypeId GetTypeId();
72
79
80 ~CoDelQueueDisc() override;
81
88
95
102
103 // Reasons for dropping packets
104 static constexpr const char* TARGET_EXCEEDED_DROP =
105 "Target exceeded drop";
106 static constexpr const char* OVERLIMIT_DROP = "Overlimit drop";
107 // Reasons for marking packets
108 static constexpr const char* TARGET_EXCEEDED_MARK =
109 "Target exceeded mark";
110 static constexpr const char* CE_THRESHOLD_EXCEEDED_MARK =
111 "CE threshold exceeded mark";
112
113 private:
114 friend class ::CoDelQueueDiscNewtonStepTest; // Test code
115 friend class ::CoDelQueueDiscControlLawTest; // Test code
122 bool DoEnqueue(Ptr<QueueDiscItem> item) override;
123
133 Ptr<QueueDiscItem> DoDequeue() override;
134
135 bool CheckConfig() override;
136
145 static uint16_t NewtonStep(uint16_t recInvSqrt, uint32_t count);
146
158 static uint32_t ControlLaw(uint32_t t, uint32_t interval, uint32_t recInvSqrt);
159
169 bool OkToDrop(Ptr<QueueDiscItem> item, uint32_t now);
170
199
207
208 void InitializeParams() override;
209
210 bool m_useEcn;
211 bool m_useL4s;
219 uint16_t m_recInvSqrt;
222};
223
224} // namespace ns3
225
226#endif /* CODEL_H */
Test 4: ControlLaw unit test - test against explicit port of Linux implementation.
Test 3: NewtonStep unit test - test against explicit port of Linux implementation.
A CoDel packet queue disc.
bool CheckConfig() override
Check whether the current configuration is correct.
uint32_t GetDropNext()
Get the time for next packet drop while in the dropping state.
static uint16_t NewtonStep(uint16_t recInvSqrt, uint32_t count)
Calculate the reciprocal square root of m_count by using Newton's method http://en....
static constexpr const char * OVERLIMIT_DROP
Overlimit dropped packet.
static uint32_t ControlLaw(uint32_t t, uint32_t interval, uint32_t recInvSqrt)
Determine the time for next drop CoDel control law is t + m_interval/sqrt(m_count).
static constexpr const char * TARGET_EXCEEDED_DROP
Sojourn time above target.
uint16_t m_recInvSqrt
Reciprocal inverse square root.
bool CoDelTimeBeforeEq(uint32_t a, uint32_t b)
Check if CoDel time a is preceding or equal to b.
void InitializeParams() override
Initialize parameters (if any) before the first packet is enqueued.
Time m_ceThreshold
Threshold above which to CE mark.
Time GetInterval()
Get the interval.
Ptr< QueueDiscItem > DoDequeue() override
Remove a packet from queue based on the current state If we are in dropping state,...
uint32_t m_minBytes
Minimum bytes in queue to allow a packet drop.
bool CoDelTimeAfterEq(uint32_t a, uint32_t b)
Check if CoDel time a is successive or equal to b.
static constexpr const char * CE_THRESHOLD_EXCEEDED_MARK
Sojourn time above CE threshold.
TracedValue< uint32_t > m_count
Number of packets dropped since entering drop state.
bool m_useL4s
True if L4S is used (ECT1 packets are marked at CE threshold)
bool OkToDrop(Ptr< QueueDiscItem > item, uint32_t now)
Determine whether a packet is OK to be dropped.
TracedValue< uint32_t > m_lastCount
Last number of packets dropped since entering drop state.
Time m_target
5 ms target queue delay
uint32_t Time2CoDel(Time t)
Return the unsigned 32-bit integer representation of the input Time object.
CoDelQueueDisc()
CoDelQueueDisc Constructor.
uint32_t m_firstAboveTime
Time to declare sojourn time above target.
Time GetTarget()
Get the target queue delay.
bool m_useEcn
True if ECN is used (packets are marked instead of being dropped)
TracedValue< bool > m_dropping
True if in dropping state.
bool CoDelTimeAfter(uint32_t a, uint32_t b)
Check if CoDel time a is successive to b.
bool CoDelTimeBefore(uint32_t a, uint32_t b)
Check if CoDel time a is preceding b.
bool DoEnqueue(Ptr< QueueDiscItem > item) override
Add a packet to the queue.
static constexpr const char * TARGET_EXCEEDED_MARK
Sojourn time above target.
Time m_interval
100 ms sliding minimum time window width
TracedValue< uint32_t > m_dropNext
Time to drop next packet.
static TypeId GetTypeId()
Get the type ID.
Smart pointer class similar to boost::intrusive_ptr.
Definition: ptr.h:77
QueueDisc is an abstract base class providing the interface and implementing the operations common to...
Definition: queue-disc.h:184
Simulation virtual time values and global simulation resolution.
Definition: nstime.h:105
Trace classes with value semantics.
Definition: traced-value.h:116
a unique identifier for an interface.
Definition: type-id.h:59
Every class exported by the ns3 library is enclosed in the ns3 namespace.
static const int CODEL_SHIFT
Number of bits discarded from the time representation.