mir/ovs
2
0
Fork 0
mirror of https://github.com/openvswitch/ovs synced 2025-08-31 22:35:15 +00:00
Code Issues Releases Wiki Activity

dpif-netdev-perf: Clarify frequency number.

Browse Source 
'dpif-netdev/pmd-perf-show' command prints the frequency number
calculated from the total number of cycles spent for iterations
for the measured period. This number could be confusing, because
users may think that it should be equal to CPU frequency, especially
on non-x86 systems where TSC frequency likely does not match with
CPU one.

Moreover, counted TSC cycles could differ from the HW TSC cycles
in case of a large number of PMD reloads, because cycles spent
outside of the main polling loop are not taken into account anywhere.
In this case the frequency will not match even TSC frequency.

Let's clarify the meaning in order to avoid this misunderstanding.
'Cycles' replaced with 'Used TSC cycles', which describes how many TSC
cycles consumed by the main polling loop. % of the total TSC cycles
now printed instead of GHz frequency, because GHz is unclear for
understanding, especially without knowing the exact TSC frequency.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>
This commit is contained in:
Ilya Maximets
2018-10-11 15:06:44 +03:00
committed by Ian Stokes
parent 21e9b77b88
commit 6794be1dee
4 changed files with 38 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
lib/dpif-netdev-perf.c
View File

@@ -170,7 +170,8 @@ pmd_perf_format_overall_stats(struct ds *str, struct pmd_perf_stats *s,
double duration)
{
uint64_t stats[PMD_N_STATS];
double us_per_cycle = 1000000.0 / get_tsc_hz();
uint64_t tsc_hz = get_tsc_hz();
double us_per_cycle = 1000000.0 / tsc_hz;
if (duration == 0) {
return;
@@ -191,26 +192,26 @@ pmd_perf_format_overall_stats(struct ds *str, struct pmd_perf_stats *s,
uint64_t busy_iter = tot_iter >= idle_iter ? tot_iter - idle_iter : 0;
ds_put_format(str,
" Cycles: %12"PRIu64" (%.2f GHz)\n"
" Iterations: %12"PRIu64" (%.2f us/it)\n"
" - idle: %12"PRIu64" (%4.1f %% cycles)\n"
" - busy: %12"PRIu64" (%4.1f %% cycles)\n",
tot_cycles, (tot_cycles / duration) / 1E9,
" Iterations: %12"PRIu64" (%.2f us/it)\n"
" - Used TSC cycles: %12"PRIu64" (%5.1f %% of total cycles)\n"
" - idle iterations: %12"PRIu64" (%5.1f %% of used cycles)\n"
" - busy iterations: %12"PRIu64" (%5.1f %% of used cycles)\n",
tot_iter, tot_cycles * us_per_cycle / tot_iter,
tot_cycles, 100.0 * (tot_cycles / duration) / tsc_hz,
idle_iter,
100.0 * stats[PMD_CYCLES_ITER_IDLE] / tot_cycles,
busy_iter,
100.0 * stats[PMD_CYCLES_ITER_BUSY] / tot_cycles);
if (rx_packets > 0) {
ds_put_format(str,
" Rx packets: %12"PRIu64" (%.0f Kpps, %.0f cycles/pkt)\n"
" Datapath passes: %12"PRIu64" (%.2f passes/pkt)\n"
" - EMC hits: %12"PRIu64" (%4.1f %%)\n"
" - SMC hits: %12"PRIu64" (%4.1f %%)\n"
" - Megaflow hits: %12"PRIu64" (%4.1f %%, %.2f subtbl lookups/"
"hit)\n"
" - Upcalls: %12"PRIu64" (%4.1f %%, %.1f us/upcall)\n"
" - Lost upcalls: %12"PRIu64" (%4.1f %%)\n",
" Rx packets: %12"PRIu64" (%.0f Kpps, %.0f cycles/pkt)\n"
" Datapath passes: %12"PRIu64" (%.2f passes/pkt)\n"
" - EMC hits: %12"PRIu64" (%5.1f %%)\n"
" - SMC hits: %12"PRIu64" (%5.1f %%)\n"
" - Megaflow hits: %12"PRIu64" (%5.1f %%, %.2f "
"subtbl lookups/hit)\n"
" - Upcalls: %12"PRIu64" (%5.1f %%, %.1f us/upcall)\n"
" - Lost upcalls: %12"PRIu64" (%5.1f %%)\n",
rx_packets, (rx_packets / duration) / 1000,
1.0 * stats[PMD_CYCLES_ITER_BUSY] / rx_packets,
passes, rx_packets ? 1.0 * passes / rx_packets : 0,
@@ -228,17 +229,16 @@ pmd_perf_format_overall_stats(struct ds *str, struct pmd_perf_stats *s,
stats[PMD_STAT_LOST],
100.0 * stats[PMD_STAT_LOST] / passes);
} else {
ds_put_format(str, " Rx packets: %12d\n", 0);
ds_put_format(str, " Rx packets: %12d\n", 0);
}
if (tx_packets > 0) {
ds_put_format(str,
" Tx packets: %12"PRIu64" (%.0f Kpps)\n"
" Tx batches: %12"PRIu64" (%.2f pkts/batch)"
"\n",
" Tx packets: %12"PRIu64" (%.0f Kpps)\n"
" Tx batches: %12"PRIu64" (%.2f pkts/batch)\n",
tx_packets, (tx_packets / duration) / 1000,
tx_batches, 1.0 * tx_packets / tx_batches);
} else {
ds_put_format(str, " Tx packets: %12d\n\n", 0);
ds_put_format(str, " Tx packets: %12d\n\n", 0);
}
}