diff options
Diffstat (limited to 'src/lib/frct.c')
| -rw-r--r-- | src/lib/frct.c | 75 |
1 files changed, 63 insertions, 12 deletions
diff --git a/src/lib/frct.c b/src/lib/frct.c index 02c101c8..bd08d86a 100644 --- a/src/lib/frct.c +++ b/src/lib/frct.c @@ -50,7 +50,11 @@ struct frcti { time_t a; time_t r; - time_t rto; /* ms */ + time_t srtt_us; /* smoothed rtt */ + time_t mdev_us; /* mdev */ + uint32_t rttseq; + struct timespec t_probe; /* probe time */ + bool probe; /* probe active */ struct frct_cr snd_cr; struct frct_cr rcv_cr; @@ -110,8 +114,11 @@ static struct frcti * frcti_create(int fd) frcti->snd_cr.inact = 3 * delta_t; frcti->snd_cr.act = now.tv_sec - (frcti->snd_cr.inact + 1); - /* Initial rto. FIXME: recalc using Karn algorithm. */ - frcti->rto = 120; + /* rtt estimator. rto is currently srtt + 2 * mdev */ + frcti->srtt_us = 0; /* updated on first ACK */ + frcti->mdev_us = 100000; /* initial rxm will be after 200 ms */ + frcti->rttseq = 0; + frcti->probe = false; if (ai.flows[fd].spec.loss == 0) { frcti->snd_cr.cflags |= FRCTFRTX; @@ -200,6 +207,18 @@ static struct frct_pci * frcti_alloc_head(struct shm_du_buff * sdb) return pci; } +static bool before(uint32_t seq1, + uint32_t seq2) +{ + return (int32_t)(seq1 - seq2) < 0; +} + +static bool after(uint32_t seq1, + uint32_t seq2) +{ + return (int32_t)(seq2 - seq1) < 0; +} + static int __frcti_snd(struct frcti * frcti, struct shm_du_buff * sdb) { @@ -219,7 +238,7 @@ static int __frcti_snd(struct frcti * frcti, if (pci == NULL) return -1; - clock_gettime(CLOCK_REALTIME_COARSE, &now); + clock_gettime(CLOCK_REALTIME, &now); pthread_rwlock_wrlock(&frcti->lock); @@ -244,12 +263,20 @@ static int __frcti_snd(struct frcti * frcti, pci->seqno = hton32(snd_cr->seqno); if (!(snd_cr->cflags & FRCTFRTX)) { snd_cr->lwe++; - } else if (now.tv_sec - rcv_cr->act <= rcv_cr->inact) { - rxmwheel_add(frcti, snd_cr->seqno, sdb); - if (rcv_cr->lwe <= rcv_cr->seqno) { - pci->flags |= FRCT_ACK; - pci->ackno = hton32(rcv_cr->seqno); - rcv_cr->lwe = rcv_cr->seqno; + } else { + if (!frcti->probe) { + frcti->rttseq = snd_cr->seqno; + frcti->t_probe = now; + frcti->probe = true; + } + + if (now.tv_sec - rcv_cr->act <= rcv_cr->inact) { + rxmwheel_add(frcti, snd_cr->seqno, sdb); + if (rcv_cr->lwe <= rcv_cr->seqno) { + pci->flags |= FRCT_ACK; + pci->ackno = hton32(rcv_cr->seqno); + rcv_cr->lwe = rcv_cr->seqno; + } } } @@ -261,6 +288,26 @@ static int __frcti_snd(struct frcti * frcti, return 0; } +static void rtt_estimator(struct frcti * frcti, + time_t mrtt_us) +{ + time_t srtt = frcti->srtt_us; + time_t mdev = frcti->mdev_us; + + if (srtt != 0) { + srtt -= (srtt >> 3); + srtt += mrtt_us >> 3; /* rtt = 7/8 rtt + 1/8 new */ + mdev -= (mdev >> 2); + mdev += ABS(srtt - mrtt_us) >> 2; + } else { + srtt = mrtt_us << 3; /* take the measured time to be rtt */ + mdev = mrtt_us >> 1; /* take half mrtt_us as deviation */ + } + + frcti->srtt_us = MAX(1U, srtt); + frcti->mdev_us = MAX(1U, mdev); +} + /* Returns 0 when idx contains a packet for the application. */ static int __frcti_rcv(struct frcti * frcti, struct shm_du_buff * sdb) @@ -280,7 +327,7 @@ static int __frcti_rcv(struct frcti * frcti, pci = (struct frct_pci *) shm_du_buff_head_release(sdb, FRCT_PCILEN); - clock_gettime(CLOCK_REALTIME_COARSE, &now); + clock_gettime(CLOCK_REALTIME, &now); pthread_rwlock_wrlock(&frcti->lock); @@ -300,7 +347,7 @@ static int __frcti_rcv(struct frcti * frcti, if (seqno == rcv_cr->seqno) { ++rcv_cr->seqno; } else { /* Out of order. */ - if ((int32_t)(seqno - rcv_cr->seqno) < 0) + if (before(seqno, rcv_cr->seqno)) goto drop_packet; if (rcv_cr->cflags & FRCTFRTX) { @@ -321,6 +368,10 @@ static int __frcti_rcv(struct frcti * frcti, /* Check for duplicate (old) acks. */ if ((int32_t)(ackno - snd_cr->lwe) >= 0) snd_cr->lwe = ackno; + if (frcti->probe && after(ackno, frcti->rttseq)) { + rtt_estimator(frcti, ts_diff_us(&frcti->t_probe, &now)); + frcti->probe = false; + } } rcv_cr->act = now.tv_sec; |