Added smooth start

SmoothStart class implemented as child of TcNewReno in a new file

src/internet/model/smooth-start.cc

@@ -0,0 +1,164 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2015 Natale Patriciello <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  U SA
+ *
+ */
+#include "tcp-congestion-ops.h"
+#include "tcp-socket-base.h"
+#include "ns3/log.h"
+#include "smooth-start.h"
+
+namespace ns3 {
+NS_LOG_COMPONENT_DEFINE ("SmoothStart");
+
+//NS_OBJECT_ENSURE_REGISTERED (SmoothStart);
+
+
+//Smooth Start
+
+/**
+ * \brief SmoothStart, a variant of SlowStart
+ *
+ * 
+ * \param tcb internal congestion state
+ * \param segmentsAcked count of segments acked
+ * \return the number of segments not considered for increasing the cWnd
+ */
+
+NS_OBJECT_ENSURE_REGISTERED (SmoothStart);
+
+TypeId
+SmoothStart::GetTypeId (void)
+{
+  static TypeId tid = TypeId ("ns3::SmoothStart")
+    .SetParent<TcpNewReno> ()
+    .SetGroupName ("Internet")
+    .AddConstructor<SmoothStart> ()
+    .AddAttribute ("GrainNumber",
+                   "Grain number used for Smooth Start",
+                   UintegerValue (2),
+                   MakeUintegerAccessor (&SmoothStart::m_grainNumber),
+                   MakeUintegerChecker<uint16_t> ()
+                   )
+    .AddAttribute ("Depth",
+                   "Depth used for Smooth Start",
+                   UintegerValue (2),
+                   MakeUintegerAccessor (&SmoothStart::m_depth),
+                   MakeUintegerChecker<uint16_t> ()
+                   );
+  return tid;
+}
+
+
+SmoothStart::SmoothStart (void) : TcpNewReno ()
+{
+  NS_LOG_FUNCTION (this);
+  m_nAcked = 0;
+  m_grainNumber = 0;
+  m_depth = 0;
+  m_ackThresh = 0;
+  m_smsThresh = 0;
+  m_firstFlag = 0;
+ }
+
+SmoothStart::SmoothStart (const SmoothStart& other)
+  : TcpNewReno (other)
+{
+  NS_LOG_FUNCTION (this);
+  m_nAcked = other.m_nAcked;
+  m_grainNumber = other.m_grainNumber;
+  m_depth = other.m_depth; 
+  m_ackThresh = other.m_ackThresh;
+  m_smsThresh  = other.m_smsThresh;
+  m_firstFlag = other.m_firstFlag;
+}
+
+SmoothStart::~SmoothStart (void)
+{
+} 
+
+uint32_t
+SmoothStart::SlowStart (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked)
+{
+  NS_LOG_FUNCTION (this << tcb << segmentsAcked);
+  m_smsThresh = tcb->m_ssThresh / pow(2,m_depth);  
+
+  NS_LOG_INFO ("Before Decision: smsThresh: "<< m_smsThresh << " ssThresh: " << tcb->m_ssThresh << " nAcked: " << m_nAcked << " Ackthresh: "<<m_ackThresh<< " cwnd: "<< tcb->m_cWnd) ;
+
+  if (segmentsAcked >= 1)
+    {
+
+      if (tcb->m_cWnd <= m_smsThresh)
+        {
+        NS_LOG_INFO("++ Slow Start ++");
+        tcb->m_cWnd += tcb->m_segmentSize;
+        NS_LOG_INFO ("In SlowStart, updated to cwnd " << tcb->m_cWnd << " ssthresh " << tcb->m_ssThresh);
+        return segmentsAcked - 1;
+        }
+
+    m_nAcked += 1;
+
+    if (m_nAcked == m_ackThresh)
+        {
+        NS_LOG_INFO("++ Smooth Start increasing cwnd++");
+        tcb->m_cWnd += tcb->m_segmentSize;
+        NS_LOG_INFO ("In SmoothStart, updated to cwnd " << tcb->m_cWnd << " ssthresh " << tcb->m_ssThresh);
+        m_ackThresh = m_ackThresh + 1;
+        m_nAcked = 0;
+        return segmentsAcked - 1;
+        }
+    else NS_LOG_INFO("++ Smooth Start not cwnd++ m_nAcked!=m_ackThresh"<< m_nAcked <<" " <<m_ackThresh);
+    return segmentsAcked - 1;    
+    }
+  return 0;
+}
+
+
+void
+SmoothStart::IncreaseWindow (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked)
+{
+  NS_LOG_FUNCTION (this << tcb << segmentsAcked);
+
+  if (tcb->m_cWnd < tcb->m_ssThresh)
+    {
+        NS_LOG_INFO ("Doing SmoothStart") ;
+        if (m_firstFlag == 0)
+                {
+                  m_firstFlag = 1 ;
+                  m_ackThresh = m_grainNumber ;           
+                }
+        segmentsAcked = SlowStart (tcb, segmentsAcked);
+    }
+
+  if (tcb->m_cWnd >= tcb->m_ssThresh)
+    {
+      m_firstFlag = 0;
+      NS_LOG_INFO("SmoothStart: Calling Congestion Avoidance");
+      CongestionAvoidance (tcb, segmentsAcked);
+    }
+
+  /* At this point, we could have segmentsAcked != 0. This because RFC says
+   * that in slow start, we should increase cWnd by min (N, SMSS); if in
+   * slow start we receive a cumulative ACK, it counts only for 1 SMSS of
+   * increase, wasting the others.
+   *
+   * // Uncorrect assert, I am sorry
+   * NS_ASSERT (segmentsAcked == 0);
+   */
+}
+
+} // namespace ns3
+

src/internet/model/smooth-start.h

@@ -0,0 +1,47 @@
+
+#ifndef SMOOTHSTART_H
+#define SMOOTHSTART_H
+
+#include "ns3/object.h"
+#include "ns3/timer.h"
+#include "ns3/tcp-socket-base.h"
+#include "tcp-congestion-ops.h"
+
+namespace ns3 {
+/**
+ * \brief The Smooth Start implementation
+ *
+ * Implements Smooth Start, a variant of Slow Start
+ * \see SlowStart
+ * Function SlowStart overridden in this class, to implement Smooth Start 
+ */
+class SmoothStart : public TcpNewReno
+{
+// Smooth Start
+  uint32_t              m_grainNumber;      //!< Grain Number in Smooth-Start
+  uint32_t              m_depth;            //!< Depth in Smooth-Start
+  uint32_t              m_ackThresh;        //!< The number of acknowledgements to be recieved before increasing cwnd
+  TracedValue<uint32_t> m_smsThresh;        //!< Smooth Start threshold
+  uint32_t              m_firstFlag;        //!< Set to zero when CongestionAvoidance starts 
+  uint32_t              m_nAcked;           //!< Number of acknowldgements recieved since last increase of cwnd
+
+protected:
+  virtual uint32_t SlowStart (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked);
+
+public:
+  static TypeId GetTypeId (void);
+  SmoothStart ();
+  /**
+   * \brief Copy constructor.
+   * \param sock object to copy.
+   */
+  SmoothStart (const SmoothStart& sock);
+
+  ~SmoothStart ();
+  virtual void IncreaseWindow (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked);
+
+};
+
+} // namespace ns3
+
+#endif // SMOOTHSTART_H