[dpdk-dev] [PATCH] rte_alarm: modify it to make it not to be affected by discontinuous jumps in the system time
Wen-Chi Yang
wolkayang at gmail.com
Fri Jun 5 04:46:36 CEST 2015
Due to eal_alarm_callback() and rte_eal_alarm_set() use gettimeofday()
to get the current time, and gettimeofday() is affected by jumps.
For example, set up a rte_alarm which will be triggerd next second (
current time + 1 second) by rte_eal_alarm_set(). And the callback
function of this rte_alarm sets up another rte_alarm which will be
triggered next second (current time + 2 second).
Once we change the system time when the callback function is triggered,
it is possiblb that rte alarm functionalities work out of expectation.
Replace gettimeofday() with clock_gettime(CLOCK_MONOTONIC_RAW, &now)
could avoid this phenomenon.
Signed-off-by: Wen-Chi Yang <wolkayang at gmail.com>
---
lib/librte_eal/linuxapp/eal/eal_alarm.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/lib/librte_eal/linuxapp/eal/eal_alarm.c b/lib/librte_eal/linuxapp/eal/eal_alarm.c
index a0eae1e..ff57323 100644
--- a/lib/librte_eal/linuxapp/eal/eal_alarm.c
+++ b/lib/librte_eal/linuxapp/eal/eal_alarm.c
@@ -99,14 +99,14 @@ static void
eal_alarm_callback(struct rte_intr_handle *hdl __rte_unused,
void *arg __rte_unused)
{
- struct timeval now;
+ struct timespec now;
struct alarm_entry *ap;
rte_spinlock_lock(&alarm_list_lk);
while ((ap = LIST_FIRST(&alarm_list)) !=NULL &&
- gettimeofday(&now, NULL) == 0 &&
+ clock_gettime(CLOCK_MONOTONIC_RAW, &now) == 0 &&
(ap->time.tv_sec < now.tv_sec || (ap->time.tv_sec == now.tv_sec &&
- ap->time.tv_usec <= now.tv_usec))){
+ (ap->time.tv_usec * NS_PER_US) <= now.tv_nsec))) {
ap->executing = 1;
ap->executing_id = pthread_self();
rte_spinlock_unlock(&alarm_list_lk);
@@ -126,11 +126,11 @@ eal_alarm_callback(struct rte_intr_handle *hdl __rte_unused,
atime.it_value.tv_sec = ap->time.tv_sec;
atime.it_value.tv_nsec = ap->time.tv_usec * NS_PER_US;
/* perform borrow for subtraction if necessary */
- if (now.tv_usec > ap->time.tv_usec)
+ if (now.tv_nsec > (ap->time.tv_usec * NS_PER_US))
atime.it_value.tv_sec--, atime.it_value.tv_nsec += US_PER_S * NS_PER_US;
atime.it_value.tv_sec -= now.tv_sec;
- atime.it_value.tv_nsec -= now.tv_usec * NS_PER_US;
+ atime.it_value.tv_nsec -= now.tv_nsec;
timerfd_settime(intr_handle.fd, 0, &atime, NULL);
}
rte_spinlock_unlock(&alarm_list_lk);
@@ -139,7 +139,7 @@ eal_alarm_callback(struct rte_intr_handle *hdl __rte_unused,
int
rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg)
{
- struct timeval now;
+ struct timespec now;
int ret = 0;
struct alarm_entry *ap, *new_alarm;
@@ -152,12 +152,12 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg)
return -ENOMEM;
/* use current time to calculate absolute time of alarm */
- gettimeofday(&now, NULL);
+ clock_gettime(CLOCK_MONOTONIC_RAW, &now);
new_alarm->cb_fn = cb_fn;
new_alarm->cb_arg = cb_arg;
- new_alarm->time.tv_usec = (now.tv_usec + us) % US_PER_S;
- new_alarm->time.tv_sec = now.tv_sec + ((now.tv_usec + us) / US_PER_S);
+ new_alarm->time.tv_usec = ((now.tv_nsec / NS_PER_US) + us) % US_PER_S;
+ new_alarm->time.tv_sec = now.tv_sec + (((now.tv_nsec / NS_PER_US) + us) / US_PER_S);
rte_spinlock_lock(&alarm_list_lk);
if (!handler_registered) {
--
1.9.1
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