For performance reasons, each thread prefer a set of queues on
each priority level, which caused starvation if preferred queues have
always some events. Added an offset to priority queue selection which
forces threads to look into other priority queues every now and then.
Signed-off-by: Petri Savolainen <petri.savolai...@nokia.com>
---
platform/linux-generic/odp_schedule.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/platform/linux-generic/odp_schedule.c
b/platform/linux-generic/odp_schedule.c
index 1aaab93..619261f 100644
--- a/platform/linux-generic/odp_schedule.c
+++ b/platform/linux-generic/odp_schedule.c
@@ -104,7 +104,9 @@ typedef struct {
int num;
int index;
int pause;
- uint32_t pktin_polls;
+ uint16_t round;
+ uint16_t prefer_offset;
+ uint16_t pktin_polls;
odp_queue_t pri_queue;
odp_event_t cmd_ev;
queue_entry_t *qe;
@@ -497,6 +499,7 @@ static int schedule(odp_queue_t *out_queue, odp_event_t
out_ev[],
odp_event_t ev;
odp_buffer_t buf;
sched_cmd_t *sched_cmd;
+ int offset = 0;
if (sched_local.num) {
ret = copy_events(out_ev, max_num);
@@ -512,13 +515,23 @@ static int schedule(odp_queue_t *out_queue, odp_event_t
out_ev[],
if (odp_unlikely(sched_local.pause))
return 0;
+ /* Each thread prefers a priority queue. This offset avoids starvation
+ * of other priority queues on low thread counts. */
+ if (odp_unlikely((sched_local.round & 0x3f) == 0)) {
+ offset = sched_local.prefer_offset;
+ sched_local.prefer_offset = (offset + 1) &
+ (QUEUES_PER_PRIO - 1);
+ }
+
+ sched_local.round++;
+
/* Schedule events */
for (i = 0; i < ODP_CONFIG_SCHED_PRIOS; i++) {
if (sched->pri_mask[i] == 0)
continue;
- id = sched_local.thr & (QUEUES_PER_PRIO - 1);
+ id = (sched_local.thr + offset) & (QUEUES_PER_PRIO - 1);
for (j = 0; j < QUEUES_PER_PRIO; j++, id++) {
odp_queue_t pri_q;
--
2.8.1
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