app/testpmd: use clock time in throughput calculation

The throughput calculation requires a counter that measures
passing of time. However, the kernel saves and restores the PMU
state when a thread is unscheduled and scheduled. This ensures
that the PMU cycles are not counted towards a thread that is
not scheduled. Hence, when RTE_ARM_EAL_RDTSC_USE_PMU is enabled,
the PMU cycles do not represent the passing of time.
This results in incorrect calculation of throughput numbers.
Use clock_gettime system call to calculate the time passed since
last call.

Bugzilla ID: 450
Fixes: 0e106980301d ("app/testpmd: show throughput in port stats")
Cc: stable@dpdk.org
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
Tested-by: Phil Yang <phil.yang@arm.com>
Tested-by: Ali Alnubani <alialnu@mellanox.com>

diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index a79019f..7501310 100644 (file)
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -54,6 +54,14 @@
 
 #define ETHDEV_FWVERS_LEN 32
 
+#ifdef CLOCK_MONOTONIC_RAW /* Defined in glibc bits/time.h */
+#define CLOCK_TYPE_ID CLOCK_MONOTONIC_RAW
+#else
+#define CLOCK_TYPE_ID CLOCK_MONOTONIC
+#endif
+
+#define NS_PER_SEC 1E9
+
 static char *flowtype_to_str(uint16_t flow_type);
 
 static const struct {
@@ -139,9 +147,10 @@ nic_stats_display(portid_t port_id)
        static uint64_t prev_pkts_tx[RTE_MAX_ETHPORTS];
        static uint64_t prev_bytes_rx[RTE_MAX_ETHPORTS];
        static uint64_t prev_bytes_tx[RTE_MAX_ETHPORTS];
-       static uint64_t prev_cycles[RTE_MAX_ETHPORTS];
+       static uint64_t prev_ns[RTE_MAX_ETHPORTS];
+       struct timespec cur_time;
        uint64_t diff_pkts_rx, diff_pkts_tx, diff_bytes_rx, diff_bytes_tx,
-                                                               diff_cycles;
+                                                               diff_ns;
        uint64_t mpps_rx, mpps_tx, mbps_rx, mbps_tx;
        struct rte_eth_stats stats;
        struct rte_port *port = &ports[port_id];
@@ -198,10 +207,17 @@ nic_stats_display(portid_t port_id)
                }
        }
 
-       diff_cycles = prev_cycles[port_id];
-       prev_cycles[port_id] = rte_rdtsc();
-       if (diff_cycles > 0)
-               diff_cycles = prev_cycles[port_id] - diff_cycles;
+       diff_ns = 0;
+       if (clock_gettime(CLOCK_TYPE_ID, &cur_time) == 0) {
+               uint64_t ns;
+
+               ns = cur_time.tv_sec * NS_PER_SEC;
+               ns += cur_time.tv_nsec;
+
+               if (prev_ns[port_id] != 0)
+                       diff_ns = ns - prev_ns[port_id];
+               prev_ns[port_id] = ns;
+       }
 
        diff_pkts_rx = (stats.ipackets > prev_pkts_rx[port_id]) ?
                (stats.ipackets - prev_pkts_rx[port_id]) : 0;
@@ -209,10 +225,10 @@ nic_stats_display(portid_t port_id)
                (stats.opackets - prev_pkts_tx[port_id]) : 0;
        prev_pkts_rx[port_id] = stats.ipackets;
        prev_pkts_tx[port_id] = stats.opackets;
-       mpps_rx = diff_cycles > 0 ?
-               diff_pkts_rx * rte_get_tsc_hz() / diff_cycles : 0;
-       mpps_tx = diff_cycles > 0 ?
-               diff_pkts_tx * rte_get_tsc_hz() / diff_cycles : 0;
+       mpps_rx = diff_ns > 0 ?
+               (double)diff_pkts_rx / diff_ns * NS_PER_SEC : 0;
+       mpps_tx = diff_ns > 0 ?
+               (double)diff_pkts_tx / diff_ns * NS_PER_SEC : 0;
 
        diff_bytes_rx = (stats.ibytes > prev_bytes_rx[port_id]) ?
                (stats.ibytes - prev_bytes_rx[port_id]) : 0;
@@ -220,10 +236,10 @@ nic_stats_display(portid_t port_id)
                (stats.obytes - prev_bytes_tx[port_id]) : 0;
        prev_bytes_rx[port_id] = stats.ibytes;
        prev_bytes_tx[port_id] = stats.obytes;
-       mbps_rx = diff_cycles > 0 ?
-               diff_bytes_rx * rte_get_tsc_hz() / diff_cycles : 0;
-       mbps_tx = diff_cycles > 0 ?
-               diff_bytes_tx * rte_get_tsc_hz() / diff_cycles : 0;
+       mbps_rx = diff_ns > 0 ?
+               (double)diff_bytes_rx / diff_ns * NS_PER_SEC : 0;
+       mbps_tx = diff_ns > 0 ?
+               (double)diff_bytes_tx / diff_ns * NS_PER_SEC : 0;
 
        printf("\n  Throughput (since last show)\n");
        printf("  Rx-pps: %12"PRIu64"          Rx-bps: %12"PRIu64"\n  Tx-pps: %12"