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ns3-datacenter
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Fix ECN calculation in HandleAckPowerQcn function

This commit is contained in:
Yupeng Chen 2024-04-27 23:53:10 +08:00
parent 3c52c8c823
commit b0ad890be2
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GPG Key ID: BB03A97DB67D4C16
2 changed files with 49 additions and 24 deletions
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70
simulator/ns-3.39/src/point-to-point/model/rdma-hw.cc
View File

@ -693,6 +693,7 @@ RdmaHw::ReceiveAck(Ptr<Packet> p, CustomHeader& ch)
break;
case CC_MODE::POWERQCN:
HandleAckPowerQcn(qp, p, ch);
break;
default:
NS_ABORT_MSG("Unknown CC mode");
break;
@ -2197,42 +2198,50 @@ RdmaHw::HandleAckPowerQcn(Ptr<RdmaQueuePair> qp, Ptr<Packet> p, CustomHeader& ch
std::mt19937 gen(rd());
std::uniform_int_distribution<> distr(0, 1000);
uint64_t prev_rtt = powerqcn_prev_rtt == 0 ? rtt : powerqcn_prev_rtt;
if (powerqcn_last_update < ch.ack.ih.GetTs())
{
powerqcn_prev_rtt = rtt;
powerqcn_last_update = Simulator::Now().GetTimeStep();
}
double rtt_gradient = (rtt - prev_rtt) / rtt_qcn_tmin;
double thresh = 0.0; // if rand(0,1000) < thresh, then ECN
powerqcn_prev_rtt = rtt;
// scale according to current RTT
bool rtt_ecn = false;
if (rtt <= rtt_qcn_tmin)
{
thresh = 0.0;
rtt_ecn = false;
}
else if (rtt <= rtt_qcn_tmax)
{
thresh = (rtt - rtt_qcn_tmin) * 1000.0 / (rtt_qcn_tmax - rtt_qcn_tmin);
auto thresh = (rtt - rtt_qcn_tmin) * 1000.0 / (rtt_qcn_tmax - rtt_qcn_tmin);
auto rand_num = distr(gen);
rtt_ecn = rand_num < thresh;
}
else
{
thresh = 1000.0;
rtt_ecn = true;
}
// scale according to RTT gradient (% of min RTT)
if (rtt_gradient <= 0)
bool gradient_ecn = false;
if (rtt_gradient <= -0.25)
{
thresh += 0.0;
}
else if (rtt_gradient >= 0.25)
{
thresh += 250.0;
gradient_ecn = false;
}
// else if (rtt_gradient <= 0.25)
// {
// auto thresh = (rtt_gradient + 0.25) * 1000.0 / 0.5;
// auto rand_num = distr(gen);
// gradient_ecn = rand_num < thresh;
// }
else
{
thresh += 1000.0 * rtt_gradient;
gradient_ecn = true;
}
bool ecn = distr(gen) < thresh;
// no worry if thresh is over 1000!
// window in mtu (1000), not in bytes / seq#
auto cwnd = qp->rttqcn.curr_win;
if (cwnd < m_mtu)
{
if (ecn)
if (rtt_ecn)
{
cwnd *= 1 - rtt_qcn_beta;
}
@ -2243,18 +2252,33 @@ RdmaHw::HandleAckPowerQcn(Ptr<RdmaQueuePair> qp, Ptr<Packet> p, CustomHeader& ch
}
else
{
if (ecn)
if (rtt_ecn)
{
cwnd -= 0.5 * m_mtu;
// cwnd -= 0.5 * m_mtu;
if (gradient_ecn)
{
cwnd -= 0.7 * m_mtu;
}
else
{
cwnd -= 0.5 * m_mtu;
}
}
else
if (!rtt_ecn)
{
// attempt to improve: multiply by 10
cwnd += m_mtu * 10.0 / cwnd;
// cwnd += m_mtu * 10.0 / cwnd;
if (gradient_ecn)
{
cwnd += m_mtu * 8.0 / cwnd;
}
else
{
cwnd += m_mtu * 20.0 / cwnd;
}
}
}
std::cout << "[RTT-QCN] node: " << m_node->GetId() << ", cwnd: " << qp->rttqcn.curr_win << "->"
<< cwnd << ", RTT: " << rtt << ", ecn: " << ecn << std::endl;
<< cwnd << ", RTT: " << rtt << ", ecn: " << rtt_ecn << gradient_ecn << std::endl;
qp->rttqcn.curr_win = cwnd;
qp->m_win = (uint32_t)cwnd;
}

3
simulator/ns-3.39/src/point-to-point/model/rdma-hw.h
View File

@ -239,7 +239,8 @@ class RdmaHw : public Object
* PowerQCN
* Improve RTT-QCN by using gradient alongside RTT
********************/
uint64_t powerqcn_prev_rtt;
uint64_t powerqcn_prev_rtt = 0; // previous RTT, used to calculate gradient
uint64_t powerqcn_last_update = 0; // last time we update prev_rtt
void HandleAckPowerQcn(Ptr<RdmaQueuePair> qp, Ptr<Packet> p, CustomHeader& ch);
};