Increase window size for latency accuracy

Accuracy of latency is obtained by writing TX accuracy for packet N
in a later packet i.e. packet N + WINDOW.
If this window is too small, packet N + WINDOW (conveying accuracy
for packet N) might arrive before packet N, resulting in no accuracy
for packet N.
This change increases this window from 64 to 8K packets.
This change should result in a higher number of packets used for
latency measurements when packets are reordered.
This change might have a performance impact as it uses more memory.

Change-Id: I1016fddb66af86605c73a24050238da41cf54152
Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>
Signed-off-by: Patrice Buriez <patrice.buriez@intel.com>

diff --git a/VNFs/DPPD-PROX/handle_gen.c b/VNFs/DPPD-PROX/handle_gen.c
index 4bf2e6e..fa16b30 100644 (file)
--- a/VNFs/DPPD-PROX/handle_gen.c
+++ b/VNFs/DPPD-PROX/handle_gen.c
@@ -114,7 +114,7 @@ struct task_gen {
                uint16_t rand_offset; /* each random has an offset*/
                uint8_t rand_len; /* # bytes to take from random (no bias introduced) */
        } rand[64];
-       uint64_t accur[64];
+       uint64_t accur[ACCURACY_WINDOW];
        uint64_t pkt_tsc_offset[64];
        struct pkt_template *pkt_template_orig; /* packet templates (from inline or from pcap) */
        struct ether_addr  src_mac;
@@ -363,11 +363,11 @@ static void task_gen_apply_all_accur_pos(struct task_gen *task, struct rte_mbuf
        if (!task->accur_pos)
                return;
 
-       /* The accuracy of task->pkt_queue_index - 64 is stored in
-          packet task->pkt_queue_index. The ID modulo 64 is the
+       /* The accuracy of task->pkt_queue_index - ACCURACY_WINDOW is stored in
+          packet task->pkt_queue_index. The ID modulo ACCURACY_WINDOW is the
           same. */
        for (uint16_t j = 0; j < count; ++j) {
-               uint32_t accuracy = task->accur[(task->pkt_queue_index + j) & 63];
+               uint32_t accuracy = task->accur[(task->pkt_queue_index + j) & (ACCURACY_WINDOW - 1)];
                task_gen_apply_accur_pos(task, pkt_hdr[j], accuracy);
        }
 }
@@ -505,7 +505,7 @@ static void task_gen_store_accuracy(struct task_gen *task, uint32_t count, uint6
        uint64_t first_accuracy_idx = task->pkt_queue_index - count;
 
        for (uint32_t i = 0; i < count; ++i) {
-               uint32_t accuracy_idx = (first_accuracy_idx + i) & 63;
+               uint32_t accuracy_idx = (first_accuracy_idx + i) & (ACCURACY_WINDOW - 1);
 
                task->accur[accuracy_idx] = accur;
        }

diff --git a/VNFs/DPPD-PROX/handle_lat.c b/VNFs/DPPD-PROX/handle_lat.c
index b4e016e..d3a52d7 100644 (file)
--- a/VNFs/DPPD-PROX/handle_lat.c
+++ b/VNFs/DPPD-PROX/handle_lat.c
@@ -35,7 +35,7 @@
 #include "prox_port_cfg.h"
 
 #define DEFAULT_BUCKET_SIZE    10
-#define ACCURACY_BUFFER_SIZE   64
+#define ACCURACY_BUFFER_SIZE   (2 * ACCURACY_WINDOW)
 
 struct lat_info {
        uint32_t rx_packet_index;
@@ -344,9 +344,9 @@ static void lat_write_latency_to_file(struct task_lat *task)
                uint64_t rx_tsc = lat_info_get_rx_tsc(lat_info);
                uint64_t tx_tsc = lat_info_get_tx_tsc(lat_info);
 
-               /* Packet n + ACCURACY_BUFFER_SIZE delivers the TX error for packet n,
-                  hence the last ACCURACY_BUFFER_SIZE packets do no have TX error. */
-               if (i + ACCURACY_BUFFER_SIZE >= task->latency_buffer_idx) {
+               /* Packet n + ACCURACY_WINDOW delivers the TX error for packet n,
+                  hence the last ACCURACY_WINDOW packets do no have TX error. */
+               if (i + ACCURACY_WINDOW >= task->latency_buffer_idx) {
                        tx_err_tsc = 0;
                }
 
@@ -616,14 +616,14 @@ static int handle_lat_bulk(struct task_base *tbase, struct rte_mbuf **mbufs, uin
                }
 
                /* If accuracy is enabled, latency is reported with a
-                  delay of ACCURACY_BUFFER_SIZE packets since the generator puts the
-                  accuracy for packet N into packet N + ACCURACY_BUFFER_SIZE. The delay
+                  delay of ACCURACY_WINDOW packets since the generator puts the
+                  accuracy for packet N into packet N + ACCURACY_WINDOW. The delay
                   ensures that all reported latencies have both rx
                   and tx error. */
                if (task->accur_pos) {
                        uint32_t tx_time_err = *(uint32_t *)(hdr + task->accur_pos);
 
-                       struct delayed_latency_entry *delayed_latency_entry = delayed_latency_get(task->delayed_latency_entries, generator_id, packet_id - ACCURACY_BUFFER_SIZE);
+                       struct delayed_latency_entry *delayed_latency_entry = delayed_latency_get(task->delayed_latency_entries, generator_id, packet_id - ACCURACY_WINDOW);
 
                        if (delayed_latency_entry) {
                                task_lat_store_lat(task,
@@ -764,11 +764,11 @@ static void init_task_lat(struct task_base *tbase, struct task_args *targ)
                        PROX_PANIC(task->delayed_latency_entries[i] == NULL, "Failed to allocate array for storing delayed latency entries\n");
                }
                if (task->unique_id_pos == 0) {
-                       /* When using accuracy feature, the accuracy from TX is written ACCURACY_BUFFER_SIZE packets later
+                       /* When using accuracy feature, the accuracy from TX is written ACCURACY_WINDOW packets later
                        * We can only retrieve the good packet if a packet id is written to it.
-                       * Otherwise we will use the packet RECEIVED ACCURACY_BUFFER_SIZE packets ago which is OK if
+                       * Otherwise we will use the packet RECEIVED ACCURACY_WINDOW packets ago which is OK if
                        * packets are not re-ordered. If packets are re-ordered, then the matching between
-                       * the tx accuracy znd the latency is wrong.
+                       * the TX accuracy and the latency is wrong.
                        */
                        plog_warn("\tWhen accuracy feature is used, a unique id should ideally also be used\n");
                }

diff --git a/VNFs/DPPD-PROX/handle_lat.h b/VNFs/DPPD-PROX/handle_lat.h
index 3cc8046..46f5e7d 100644 (file)
--- a/VNFs/DPPD-PROX/handle_lat.h
+++ b/VNFs/DPPD-PROX/handle_lat.h
@@ -25,6 +25,10 @@
 #include "clock.h"
 
 #define LATENCY_ACCURACY       1
+// If ACCURACY_WINDOW is too small, the accuracy for packet N can be received by lat BEFORE
+// packet N is received (re-ordering) resulting in accuracy being unused
+// 8192 packets is equivalent to 550 micro-seconds at 10Gbps for 64 bytes packets
+#define ACCURACY_WINDOW                8192
 
 struct lat_test {
        uint64_t tot_all_pkts;