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