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serialqueue: Limit message transmission to available receive buffer size

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If the mcu is using a traditional serial port, then only send a new
message block if there is space available in the mcu receive buffer.
This should make it significantly less likely that high load on the
mcu will result in retransmits.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor
2018-05-28 09:42:59 -04:00
parent 0728c1a8be
commit d798fae20b
4 changed files with 32 additions and 5 deletions
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23
klippy/chelper/serialqueue.c
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@@ -357,6 +357,7 @@ struct serialqueue {
pthread_cond_t cond;
int receive_waiting;
// Baud / clock tracking
int receive_window;
double baud_adjust, idle_time;
double est_freq, last_clock_time;
uint64_t last_clock;
@@ -368,7 +369,7 @@ struct serialqueue {
double srtt, rttvar, rto;
// Pending transmission message queues
struct list_head pending_queues;
int ready_bytes, stalled_bytes, need_ack_bytes;
int ready_bytes, stalled_bytes, need_ack_bytes, last_ack_bytes;
uint64_t need_kick_clock;
// Received messages
struct list_head receive_queue;
@@ -458,6 +459,7 @@ update_receive_seq(struct serialqueue *sq, double eventtime, uint64_t rseq)
if (rseq == sent_seq) {
// Found sent message corresponding with the received sequence
sq->last_receive_sent_time = sent->receive_time;
sq->last_ack_bytes = sent->len;
break;
}
}
@@ -694,11 +696,18 @@ build_and_send_command(struct serialqueue *sq, double eventtime)
static double
check_send_command(struct serialqueue *sq, double eventtime)
{
if ((sq->send_seq - sq->receive_seq >= MESSAGE_SEQ_MASK
|| (sq->need_ack_bytes - 2*MESSAGE_MAX) * sq->baud_adjust > sq->srtt)
if (sq->send_seq - sq->receive_seq >= MESSAGE_SEQ_MASK
&& sq->receive_seq != (uint64_t)-1)
// Need an ack before more messages can be sent
return PR_NEVER;
if (sq->send_seq > sq->receive_seq && sq->receive_window) {
int need_ack_bytes = sq->need_ack_bytes + MESSAGE_MAX;
if (sq->last_ack_seq < sq->receive_seq)
need_ack_bytes += sq->last_ack_bytes;
if (need_ack_bytes > sq->receive_window)
// Wait for ack from past messages before sending next message
return PR_NEVER;
}
// Check for stalled messages now ready
double idletime = eventtime > sq->idle_time ? eventtime : sq->idle_time;
@@ -1021,6 +1030,14 @@ serialqueue_set_baud_adjust(struct serialqueue *sq, double baud_adjust)
pthread_mutex_unlock(&sq->lock);
}
void
serialqueue_set_receive_window(struct serialqueue *sq, int receive_window)
{
pthread_mutex_lock(&sq->lock);
sq->receive_window = receive_window;
pthread_mutex_unlock(&sq->lock);
}
// Set the estimated clock rate of the mcu on the other end of the
// serial port
void