Re: [lng-odp] [PATCH v2 5/6] linux-gen: sched: increase max dequeue batch size

[Maxim Uvarov]

On 09/05/16 13:09, Petri Savolainen wrote:

Increased queue dequeue batch size to improve throughput. Low
priority queues have smaller batch size than high/default, so
that head of line blocking latency is limited.

Signed-off-by: Petri Savolainen <petri.savolai...@nokia.com>
---
  .../linux-generic/include/odp_schedule_internal.h  |  2 +-
  platform/linux-generic/odp_schedule.c              | 34 +++++++++++++---------
  2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/platform/linux-generic/include/odp_schedule_internal.h 
b/platform/linux-generic/include/odp_schedule_internal.h
index 1b6ae93..d6cfdb4 100644
--- a/platform/linux-generic/include/odp_schedule_internal.h
+++ b/platform/linux-generic/include/odp_schedule_internal.h
@@ -12,7 +12,7 @@ extern "C" {
  #endif

/* Maximum number of dequeues */

-#define MAX_DEQ 4
+#define MAX_DEQ 8

is there any dependency between MAX_DEQ
and

#define MAX_PKTIN 16

from patch 3/6? Can we specify this in #define ?

Maxim.

  typedef struct {
        int thr;
diff --git a/platform/linux-generic/odp_schedule.c 
b/platform/linux-generic/odp_schedule.c
index 95ba13f..d4eb13f 100644
--- a/platform/linux-generic/odp_schedule.c
+++ b/platform/linux-generic/odp_schedule.c
@@ -586,12 +586,13 @@ static inline int copy_events(odp_event_t out_ev[], 
unsigned int max)
   * Schedule queues
   */
  static int do_schedule(odp_queue_t *out_queue, odp_event_t out_ev[],
-                      unsigned int max_num, unsigned int max_deq)
+                      unsigned int max_num)
  {
-       int i, j;
+       int prio, i;
        int ret;
        int id;
        int offset = 0;
+       unsigned int max_deq = MAX_DEQ;
        uint32_t qi;

if (sched_local.num) {

@@ -619,14 +620,14 @@ static int do_schedule(odp_queue_t *out_queue, 
odp_event_t out_ev[],
        sched_local.round++;

/* Schedule events */

-       for (i = 0; i < NUM_PRIO; i++) {
+       for (prio = 0; prio < NUM_PRIO; prio++) {

- if (sched->pri_mask[i] == 0)

+               if (sched->pri_mask[prio] == 0)
                        continue;

id = (sched_local.thr + offset) & (QUEUES_PER_PRIO - 1); - for (j = 0; j < QUEUES_PER_PRIO;) {

+               for (i = 0; i < QUEUES_PER_PRIO;) {
                        int num;
                        int grp;
                        int ordered;
@@ -637,20 +638,20 @@ static int do_schedule(odp_queue_t *out_queue, 
odp_event_t out_ev[],
                                id = 0;

/* No queues created for this priority queue */

-                       if (odp_unlikely((sched->pri_mask[i] & (1 << id))
+                       if (odp_unlikely((sched->pri_mask[prio] & (1 << id))
                            == 0)) {
-                               j++;
+                               i++;
                                id++;
                                continue;
                        }

/* Get queue index from the priority queue */

-                       ring = &sched->prio_q[i][id].ring;
+                       ring = &sched->prio_q[prio][id].ring;
                        qi   = ring_deq(ring, PRIO_QUEUE_MASK);

/* Priority queue empty */

                        if (qi == RING_EMPTY) {
-                               j++;
+                               i++;
                                id++;
                                continue;
                        }
@@ -665,11 +666,16 @@ static int do_schedule(odp_queue_t *out_queue, 
odp_event_t out_ev[],
                                 */
                                ring_enq(ring, PRIO_QUEUE_MASK, qi);

- j++;

+                               i++;
                                id++;
                                continue;
                        }

+ /* Low priorities have smaller batch size to limit

+                        * head of line blocking latency. */
+                       if (odp_unlikely(prio > ODP_SCHED_PRIO_DEFAULT))
+                               max_deq = MAX_DEQ / 2;
+
                        ordered = sched_cb_queue_is_ordered(qi);

/* For ordered queues we want consecutive events to

@@ -782,14 +788,14 @@ static int do_schedule(odp_queue_t *out_queue, 
odp_event_t out_ev[],

static int schedule_loop(odp_queue_t *out_queue, uint64_t wait,

                         odp_event_t out_ev[],
-                        unsigned int max_num, unsigned int max_deq)
+                        unsigned int max_num)
  {
        odp_time_t next, wtime;
        int first = 1;
        int ret;

while (1) {

-               ret = do_schedule(out_queue, out_ev, max_num, max_deq);
+               ret = do_schedule(out_queue, out_ev, max_num);

if (ret)

                        break;
@@ -820,7 +826,7 @@ static odp_event_t schedule(odp_queue_t *out_queue, 
uint64_t wait)

ev = ODP_EVENT_INVALID; - schedule_loop(out_queue, wait, &ev, 1, MAX_DEQ);

+       schedule_loop(out_queue, wait, &ev, 1);

return ev;

  }
@@ -828,7 +834,7 @@ static odp_event_t schedule(odp_queue_t *out_queue, 
uint64_t wait)
  static int schedule_multi(odp_queue_t *out_queue, uint64_t wait,
                          odp_event_t events[], int num)
  {
-       return schedule_loop(out_queue, wait, events, num, MAX_DEQ);
+       return schedule_loop(out_queue, wait, events, num);
  }

static void schedule_pause(void)