[v3,1/3] app/testpmd: clock gettime call in throughput calculation
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Commit Message
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: zhihong.wang@intel.com
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>
---
v3:
1) Dropped 'noisy vnf' patch, will add with future Dharmik's patch
2) Dropped flow gen patch, send out a separate one if there is
consensus on the mailing list
3) Changed the logic to display burst stats to make it easier
to understand (Ferruh)
v2: Updated commit log in 1/5 (Jerin)
app/test-pmd/config.c | 44 +++++++++++++++++++++++++++++--------------
1 file changed, 30 insertions(+), 14 deletions(-)
Comments
On 7/7/2020 12:32 AM, Honnappa Nagarahalli wrote:
> 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: zhihong.wang@intel.com
> 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>
Series applied to dpdk-next-net/master, thanks.
@@ -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 {
@@ -136,9 +144,10 @@ 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];
@@ -195,10 +204,17 @@ 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;
@@ -206,10 +222,10 @@ 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;
@@ -217,10 +233,10 @@ 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"