rttest.h

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#ifndef NDNDPDK_CORE_RTTEST_H
#define NDNDPDK_CORE_RTTEST_H

 
#include "../dpdk/tsc.h"
#include "rttest-enum.h"

typedef struct RttValue {
  float sRtt;
  float rttVar;
} RttValue;
static_assert(sizeof(RttValue) == sizeof(uint64_t), "");
 
__attribute__((nonnull)) static __rte_always_inline TscDuration
RttValue_RTO(RttValue* rttv) {
  return rttv->sRtt + RttEstK * rttv->rttVar;
}
 
#ifndef __BPF__
 
#define RttEstAlpha (1.0 * RttEstAlphaDividend / RttEstAlphaDivisor)
#define RttEstBeta (1.0 * RttEstBetaDividend / RttEstBetaDivisor)

__attribute__((nonnull)) static inline void
RttValue_Push(RttValue* rttv, TscDuration rtt) {
  if (unlikely(*(uint64_t*)rttv == 0)) {
    rttv->sRtt = rtt;
    rttv->rttVar = rtt / 2.0;
  } else {
    rttv->rttVar = (1.0 - RttEstBeta) * rttv->rttVar + RttEstBeta * fabs(rttv->sRtt - rtt);
    rttv->sRtt = (1.0 - RttEstAlpha) * rttv->sRtt + RttEstAlpha * rtt;
  }
}
 
extern TscDuration RttEstTscMinRto;
extern TscDuration RttEstTscMaxRto;

typedef struct RttEst {
  RttValue rttv;
  TscDuration rto;
  TscDuration last; // last input RTT (for external sampling only)
  TscTime next_;    // when to take next RTT sample
} RttEst;
 
__attribute__((nonnull)) void
RttEst_Init(RttEst* rtte);
 
__attribute__((nonnull)) static inline void
RttEst_SetRTO_(RttEst* rtte, TscDuration rto) {
  rtte->rto = CLAMP(rto, RttEstTscMinRto, RttEstTscMaxRto);
}

__attribute__((nonnull)) static inline void
RttEst_Push(RttEst* rtte, TscTime now, TscDuration rtt) {
  rtte->last = rtt;
  if (likely(rtte->next_ > now)) {
    return;
  }
 
  RttValue_Push(&rtte->rttv, rtt);
  RttEst_SetRTO_(rtte, RttValue_RTO(&rtte->rttv));
  rtte->next_ = now + rtte->rttv.sRtt;
}

__attribute__((nonnull)) static inline void
RttEst_Backoff(RttEst* rtte) {
  RttEst_SetRTO_(rtte, rtte->rto * 2);
}
 
#endif // __BPF__
 
#endif // NDNDPDK_CORE_RTTEST_H