In order to obtain a precise TX SYNC frequency we need to use a periodic
timer facility instead to reconfigure the timer on every expiration.
The solution consists to configure the it_interval field of the
itimerspec structure (see timerfd_create(2) man page) only when the port
goes into Master role and avoiding to call timerfd_settime() on timer
expiration.
---
port.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/port.c b/port.c
index afbf8ad..70d2f16 100644
--- a/port.c
+++ b/port.c
@@ -231,7 +231,7 @@ struct fdarray *port_fda(struct port *port)
return &port->fda;
}
-int set_tmo_log(int fd, unsigned int scale, int log_seconds)
+static int set_tmo_log_periodic(int fd, unsigned int scale, int log_seconds,
bool periodic)
{
struct itimerspec tmo = {
{0, 0}, {0, 0}
@@ -255,9 +255,19 @@ int set_tmo_log(int fd, unsigned int scale, int
log_seconds)
} else
tmo.it_value.tv_sec = scale * (1 << log_seconds);
+ if (periodic) {
+ tmo.it_interval.tv_nsec = tmo.it_value.tv_nsec;
+ tmo.it_interval.tv_sec = tmo.it_value.tv_sec;
+ }
+
return timerfd_settime(fd, 0, &tmo, NULL);
}
+int set_tmo_log(int fd, unsigned int scale, int log_seconds)
+{
+ return set_tmo_log_periodic(fd, scale, log_seconds, false);
+}
+
int set_tmo_lin(int fd, int seconds)
{
struct itimerspec tmo = {
@@ -1297,7 +1307,7 @@ int port_set_sync_rx_tmo(struct port *p)
static int port_set_sync_tx_tmo(struct port *p)
{
- return set_tmo_log(p->fda.fd[FD_SYNC_TX_TIMER], 1, p->logSyncInterval);
+ return set_tmo_log_periodic(p->fda.fd[FD_SYNC_TX_TIMER], 1,
p->logSyncInterval, true);
}
void port_show_transition(struct port *p, enum port_state next,
@@ -2935,7 +2945,6 @@ static enum fsm_event bc_event(struct port *p, int
fd_index)
case FD_SYNC_TX_TIMER:
pr_debug("%s: master sync timeout", p->log_name);
timerfd_flush(p, fd, "master sync timeout");
- port_set_sync_tx_tmo(p);
p->service_stats.master_sync_timeout++;
return port_tx_sync(p, NULL, p->seqnum.sync++) ?
EV_FAULT_DETECTED : EV_NONE;
--
2.41.0
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