A precalculated table is more flexible for tunning weights
than hard coding. As future development, the table may be
updated with different weights at init or run time.
Signed-off-by: Petri Savolainen <petri.savolai...@linaro.org>
---
platform/linux-generic/odp_schedule.c | 51 ++++++++++++++++++++++++++---------
1 file changed, 39 insertions(+), 12 deletions(-)
diff --git a/platform/linux-generic/odp_schedule.c
b/platform/linux-generic/odp_schedule.c
index cd5bf21..e7079b9 100644
--- a/platform/linux-generic/odp_schedule.c
+++ b/platform/linux-generic/odp_schedule.c
@@ -39,6 +39,13 @@ ODP_STATIC_ASSERT((ODP_SCHED_PRIO_NORMAL > 0) &&
/* Priority queues per priority */
#define QUEUES_PER_PRIO 4
+/* A thread polls a non preferred sched queue every this many polls
+ * of the prefer queue. */
+#define PREFER_RATIO 64
+
+/* Size of poll weight table */
+#define WEIGHT_TBL_SIZE ((QUEUES_PER_PRIO - 1) * PREFER_RATIO)
+
/* Packet input poll cmd queues */
#define PKTIO_CMD_QUEUES 4
@@ -142,7 +149,6 @@ typedef struct {
int index;
int pause;
uint16_t round;
- uint16_t prefer_offset;
uint16_t pktin_polls;
uint32_t queue_index;
odp_queue_t queue;
@@ -157,6 +163,8 @@ typedef struct {
ordered_stash_t stash[MAX_ORDERED_STASH];
} ordered;
+ uint8_t weight_tbl[WEIGHT_TBL_SIZE];
+
} sched_local_t;
/* Priority queue */
@@ -237,11 +245,29 @@ static inline void schedule_release_context(void);
static void sched_local_init(void)
{
+ int i;
+ uint8_t id;
+ uint8_t offset = 0;
+
memset(&sched_local, 0, sizeof(sched_local_t));
sched_local.thr = odp_thread_id();
sched_local.queue = ODP_QUEUE_INVALID;
sched_local.queue_index = PRIO_QUEUE_EMPTY;
+
+ id = sched_local.thr & (QUEUES_PER_PRIO - 1);
+
+ for (i = 0; i < WEIGHT_TBL_SIZE; i++) {
+ sched_local.weight_tbl[i] = id;
+
+ if (i % PREFER_RATIO == 0) {
+ offset++;
+ sched_local.weight_tbl[i] = (id + offset) &
+ (QUEUES_PER_PRIO - 1);
+ if (offset == QUEUES_PER_PRIO - 1)
+ offset = 0;
+ }
+ }
}
static int schedule_init_global(void)
@@ -670,10 +696,10 @@ static int do_schedule(odp_queue_t *out_queue,
odp_event_t out_ev[],
{
int prio, i;
int ret;
- int id;
- int offset = 0;
+ int id, first;
unsigned int max_deq = MAX_DEQ;
uint32_t qi;
+ uint16_t round;
if (sched_local.num) {
ret = copy_events(out_ev, max_num);
@@ -689,15 +715,15 @@ static int do_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);
- }
+ /* Each thread prefers a priority queue. Poll weight table avoids
+ * starvation of other priority queues on low thread counts. */
+ round = sched_local.round + 1;
+
+ if (odp_unlikely(round == WEIGHT_TBL_SIZE))
+ round = 0;
- sched_local.round++;
+ sched_local.round = round;
+ first = sched_local.weight_tbl[round];
/* Schedule events */
for (prio = 0; prio < NUM_PRIO; prio++) {
@@ -705,7 +731,8 @@ static int do_schedule(odp_queue_t *out_queue, odp_event_t
out_ev[],
if (sched->pri_mask[prio] == 0)
continue;
- id = (sched_local.thr + offset) & (QUEUES_PER_PRIO - 1);
+ /* Select the first ring based on weights */
+ id = first;
for (i = 0; i < QUEUES_PER_PRIO;) {
int num;
--
2.8.1
