From: Alan Dewar <alan.de...@att.com>
The WRR code calculates the lowest common denominator between the four
WRR weights as a uint32_t value and divides the LCD by each of the WRR
weights and casts the results as a uint8_t. This casting can cause
the ratios of the computed wrr costs to be wrong. For example with
WRR weights of 3, 5, 7 and 11, the LCD is computed to be
1155. The WRR costs get computed as:
1155/3 = 385, 1155/5 = 231, 1155/7 = 165, 1155/11 = 105.
When the value 385 is cast into an uint8_t it ends up as 129.
Rather than casting straight into a uint8_t, this patch shifts the
computed WRR costs right so that the largest value is only eight bits
wide.
In grinder_schedule, the packet length is multiplied by the WRR cost
and added to the grinder's wrr_tokens value. The grinder's wrr_tokens
field is a uint16_t, so combination of a packet length of 1500 bytes
and a wrr cost of 44 will overflow this field on the first packet.
This patch increases the width of the grinder's wrr_tokens and
wrr_mask fields from uint16_t to uint32_t.
In grinder_wrr_store, the remaining tokens in the grinder's wrr_tokens
array are copied to the appropriate pipe's wrr_tokens array. However
the pipe's wrr_tokens array is only a uint8_t array so unused tokens
were quite frequently lost which upsets the balance of traffic across
the four WRR queues.
This patch increases the width of the pipe's wrr_tokens array from
a uint8_t to uint32_t.
Signed-off-by: Alan Dewar <alan.de...@att.com>
---
lib/librte_sched/rte_sched.c | 57 ++++++++++++++++++++++++++-----------
lib/librte_sched/rte_sched_common.h | 15 ++++++++++
2 files changed, 55 insertions(+), 17 deletions(-)
diff --git a/lib/librte_sched/rte_sched.c b/lib/librte_sched/rte_sched.c
index 7252f85..a65c98f 100644
--- a/lib/librte_sched/rte_sched.c
+++ b/lib/librte_sched/rte_sched.c
@@ -130,7 +130,7 @@ struct rte_sched_pipe {
uint32_t tc_credits[RTE_SCHED_TRAFFIC_CLASSES_PER_PIPE];
/* Weighted Round Robin (WRR) */
- uint8_t wrr_tokens[RTE_SCHED_QUEUES_PER_PIPE];
+ uint32_t wrr_tokens[RTE_SCHED_QUEUES_PER_PIPE];
/* TC oversubscription */
uint32_t tc_ov_credits;
@@ -205,8 +205,8 @@ struct rte_sched_grinder {
struct rte_mbuf *pkt;
/* WRR */
- uint16_t wrr_tokens[RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS];
- uint16_t wrr_mask[RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS];
+ uint32_t wrr_tokens[RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS];
+ uint32_t wrr_mask[RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS];
uint8_t wrr_cost[RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS];
};
@@ -542,6 +542,17 @@ rte_sched_time_ms_to_bytes(uint32_t time_ms, uint32_t rate)
return time;
}
+static uint32_t rte_sched_reduce_to_byte(uint32_t value)
+{
+ uint32_t shift = 0;
+
+ while (value & 0xFFFFFF00) {
+ value >>= 1;
+ shift++;
+ }
+ return shift;
+}
+
static void
rte_sched_port_config_pipe_profile_table(struct rte_sched_port *port, struct
rte_sched_port_params *params)
{
@@ -583,6 +594,8 @@ rte_sched_port_config_pipe_profile_table(struct
rte_sched_port *port, struct rte
uint32_t wrr_cost[RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS];
uint32_t lcd, lcd1, lcd2;
uint32_t qindex;
+ uint32_t low_pos;
+ uint32_t shift;
qindex = j * RTE_SCHED_QUEUES_PER_TRAFFIC_CLASS;
@@ -594,16 +607,22 @@ rte_sched_port_config_pipe_profile_table(struct
rte_sched_port *port, struct rte
lcd1 = rte_get_lcd(wrr_cost[0], wrr_cost[1]);
lcd2 = rte_get_lcd(wrr_cost[2], wrr_cost[3]);
lcd = rte_get_lcd(lcd1, lcd2);
+ low_pos = rte_min_pos_4_u32(wrr_cost);
wrr_cost[0] = lcd / wrr_cost[0];
wrr_cost[1] = lcd / wrr_cost[1];
wrr_cost[2] = lcd / wrr_cost[2];
wrr_cost[3] = lcd / wrr_cost[3];
- dst->wrr_cost[qindex] = (uint8_t) wrr_cost[0];
- dst->wrr_cost[qindex + 1] = (uint8_t) wrr_cost[1];
- dst->wrr_cost[qindex + 2] = (uint8_t) wrr_cost[2];
- dst->wrr_cost[qindex + 3] = (uint8_t) wrr_cost[3];
+ shift = rte_sched_reduce_to_byte(wrr_cost[low_pos]);
+ dst->wrr_cost[qindex] = (uint8_t) (wrr_cost[0] >>
+ shift);
+ dst->wrr_cost[qindex + 1] = (uint8_t) (wrr_cost[1] >>
+ shift);
+ dst->wrr_cost[qindex + 2] = (uint8_t) (wrr_cost[2] >>
+ shift);
+ dst->wrr_cost[qindex + 3] = (uint8_t) (wrr_cost[3] >>
+ shift);
}
rte_sched_port_log_pipe_profile(port, i);
@@ -1941,15 +1960,19 @@ grinder_wrr_load(struct rte_sched_port *port, uint32_t
pos)
qindex = tc_index * 4;
- grinder->wrr_tokens[0] = ((uint16_t) pipe->wrr_tokens[qindex]) <<
RTE_SCHED_WRR_SHIFT;
- grinder->wrr_tokens[1] = ((uint16_t) pipe->wrr_tokens[qindex + 1]) <<
RTE_SCHED_WRR_SHIFT;
- grinder->wrr_tokens[2] = ((uint16_t) pipe->wrr_tokens[qindex + 2]) <<
RTE_SCHED_WRR_SHIFT;
- grinder->wrr_tokens[3] = ((uint16_t) pipe->wrr_tokens[qindex + 3]) <<
RTE_SCHED_WRR_SHIFT;
+ grinder->wrr_tokens[0] = pipe->wrr_tokens[qindex] <<
+ RTE_SCHED_WRR_SHIFT;
+ grinder->wrr_tokens[1] = pipe->wrr_tokens[qindex + 1] <<
+ RTE_SCHED_WRR_SHIFT;
+ grinder->wrr_tokens[2] = pipe->wrr_tokens[qindex + 2] <<
+ RTE_SCHED_WRR_SHIFT;
+ grinder->wrr_tokens[3] = pipe->wrr_tokens[qindex + 3] <<
+ RTE_SCHED_WRR_SHIFT;
- grinder->wrr_mask[0] = (qmask & 0x1) * 0xFFFF;
- grinder->wrr_mask[1] = ((qmask >> 1) & 0x1) * 0xFFFF;
- grinder->wrr_mask[2] = ((qmask >> 2) & 0x1) * 0xFFFF;
- grinder->wrr_mask[3] = ((qmask >> 3) & 0x1) * 0xFFFF;
+ grinder->wrr_mask[0] = (qmask & 0x1) * 0xFFFFFFFF;
+ grinder->wrr_mask[1] = ((qmask >> 1) & 0x1) * 0xFFFFFFFF;
+ grinder->wrr_mask[2] = ((qmask >> 2) & 0x1) * 0xFFFFFFFF;
+ grinder->wrr_mask[3] = ((qmask >> 3) & 0x1) * 0xFFFFFFFF;
grinder->wrr_cost[0] = pipe_params->wrr_cost[qindex];
grinder->wrr_cost[1] = pipe_params->wrr_cost[qindex + 1];
@@ -1981,14 +2004,14 @@ static inline void
grinder_wrr(struct rte_sched_port *port, uint32_t pos)
{
struct rte_sched_grinder *grinder = port->grinder + pos;
- uint16_t wrr_tokens_min;
+ uint32_t wrr_tokens_min;
grinder->wrr_tokens[0] |= ~grinder->wrr_mask[0];
grinder->wrr_tokens[1] |= ~grinder->wrr_mask[1];
grinder->wrr_tokens[2] |= ~grinder->wrr_mask[2];
grinder->wrr_tokens[3] |= ~grinder->wrr_mask[3];
- grinder->qpos = rte_min_pos_4_u16(grinder->wrr_tokens);
+ grinder->qpos = rte_min_pos_4_u32(grinder->wrr_tokens);
wrr_tokens_min = grinder->wrr_tokens[grinder->qpos];
grinder->wrr_tokens[0] -= wrr_tokens_min;
diff --git a/lib/librte_sched/rte_sched_common.h
b/lib/librte_sched/rte_sched_common.h
index aed144b..a3c6bc2 100644
--- a/lib/librte_sched/rte_sched_common.h
+++ b/lib/librte_sched/rte_sched_common.h
@@ -77,6 +77,21 @@ rte_min_pos_4_u16(uint16_t *x)
return pos0;
}
+static inline uint32_t
+rte_min_pos_4_u32(uint32_t *x)
+{
+ uint32_t pos0 = 0;
+ uint32_t pos1 = 2;
+
+ if (x[1] <= x[0])
+ pos0 = 1;
+ if (x[3] <= x[2])
+ pos1 = 3;
+ if (x[pos1] <= x[pos0])
+ pos0 = pos1;
+
+ return pos0;
+}
#endif
/*
--
2.1.4
