Currently, the interrupt status notification prevents log spam by
remembering whether previous interrupt wakeup was due to traffic or due
to timeout expiring. However, it is a single variable that can
potentially be accessed from multiple threads, so it is not thread-safe.
Fix it by having per-lcore interrupt status.
Fixes: f4d1e19c293d ("examples/l3fwd-power: add Rx interrupt timeout")
Cc: anatoly.bura...@intel.com
Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---
Notes:
v2:
- Fix confusing variable naming
examples/l3fwd-power/main.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/examples/l3fwd-power/main.c b/examples/l3fwd-power/main.c
index d0e6c9bd77..526af0db29 100644
--- a/examples/l3fwd-power/main.c
+++ b/examples/l3fwd-power/main.c
@@ -821,20 +821,23 @@ power_freq_scaleup_heuristic(unsigned lcore_id,
* 0 on success
*/
static int
-sleep_until_rx_interrupt(int num)
+sleep_until_rx_interrupt(int num, int lcore)
{
/*
* we want to track when we are woken up by traffic so that we can go
- * back to sleep again without log spamming.
+ * back to sleep again without log spamming. Avoid cache line sharing
+ * to prevent threads stepping on each others' toes.
*/
- static bool timeout;
+ static struct {
+ bool wakeup;
+ } __rte_cache_aligned status[RTE_MAX_LCORE];
struct rte_epoll_event event[num];
int n, i;
uint16_t port_id;
uint8_t queue_id;
void *data;
- if (!timeout) {
+ if (status[lcore].wakeup) {
RTE_LOG(INFO, L3FWD_POWER,
"lcore %u sleeps until interrupt triggers\n",
rte_lcore_id());
@@ -851,7 +854,7 @@ sleep_until_rx_interrupt(int num)
" port %d queue %d\n",
rte_lcore_id(), port_id, queue_id);
}
- timeout = n == 0;
+ status[lcore].wakeup = n != 0;
return 0;
}
@@ -1050,7 +1053,8 @@ static int main_intr_loop(__rte_unused void *dummy)
if (intr_en) {
turn_on_off_intr(qconf, 1);
sleep_until_rx_interrupt(
- qconf->n_rx_queue);
+ qconf->n_rx_queue,
+ lcore_id);
turn_on_off_intr(qconf, 0);
/**
* start receiving packets immediately
@@ -1473,7 +1477,8 @@ main_legacy_loop(__rte_unused void *dummy)
if (intr_en) {
turn_on_off_intr(qconf, 1);
sleep_until_rx_interrupt(
- qconf->n_rx_queue);
+ qconf->n_rx_queue,
+ lcore_id);
turn_on_off_intr(qconf, 0);
/**
* start receiving packets immediately
--
2.17.1
