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serialqueue: Improve timing of multiple retransmits 

If a retransmit is triggered by a nak, then it is not necessary to
increase the rto.  The next retransmit time should be based on the
expected reception of the first retransmitted message, not the last.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-07-21 21:26:14 -04:00
parent 7faa5fe233
commit 61325c0a14
1 changed files with 12 additions and 8 deletions
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14
klippy/serialqueue.c
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@ -102,14 +102,12 @@ pollreactor_add_timer(struct pollreactor *pr, int pos, void *callback)
pr->timers[pos].waketime = PR_NEVER;
}
#if 0
// Return the last schedule wake-up time for a timer
static double
pollreactor_get_timer(struct pollreactor *pr, int pos)
{
return pr->timers[pos].waketime;
}
#endif
// Set the wake-up time for a given timer
static void
@ -568,12 +566,14 @@ retransmit_event(struct serialqueue *sq, double eventtime)
// Retransmit all pending messages
uint8_t buf[MESSAGE_MAX * MESSAGE_SEQ_MASK + 1];
int buflen = 0;
int buflen = 0, first_buflen = 0;
buf[buflen++] = MESSAGE_SYNC;
struct queue_message *qm;
list_for_each_entry(qm, &sq->sent_queue, node) {
memcpy(&buf[buflen], qm->msg, qm->len);
buflen += qm->len;
if (!first_buflen)
first_buflen = qm->len;
}
ret = write(sq->serial_fd, buf, buflen);
if (ret < 0)
@ -581,13 +581,17 @@ retransmit_event(struct serialqueue *sq, double eventtime)
sq->bytes_retransmit += buflen;
// Update rto
if (pollreactor_get_timer(&sq->pr, SQPT_RETRANSMIT) != PR_NOW) {
sq->rto *= 2.0;
if (sq->rto > MAX_RTO)
sq->rto = MAX_RTO;
}
sq->retransmit_seq = sq->send_seq;
sq->rtt_sample_seq = 0;
sq->idle_time = eventtime + buflen * sq->baud_adjust;
double waketime = sq->idle_time + sq->rto;
if (eventtime > sq->idle_time)
sq->idle_time = eventtime;
double waketime = sq->idle_time + first_buflen * sq->baud_adjust + sq->rto;
sq->idle_time += buflen * sq->baud_adjust;
pthread_mutex_unlock(&sq->lock);
return waketime;