[ovs-dev,v2] dpif-netdev-perf: Clarify frequency number.

Message ID 20181011120644.19071-1-i.maximets@samsung.com
State Accepted
Delegated to: Ian Stokes
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Series
  • [ovs-dev,v2] dpif-netdev-perf: Clarify frequency number.
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Commit Message

Ilya Maximets Oct. 11, 2018, 12:06 p.m.
'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>
---

Version 2:
	* Fixed OSX manpage build failure due to missing of .EX and .EE.

 lib/dpif-netdev-perf.c      | 36 ++++++++++++++++++------------------
 lib/dpif-netdev-unixctl.man | 28 +++++++++++++++-------------
 manpages.mk                 |  2 ++
 vswitchd/ovs-vswitchd.8.in  |  6 +-----
 4 files changed, 36 insertions(+), 36 deletions(-)

Patch

diff --git a/lib/dpif-netdev-perf.c b/lib/dpif-netdev-perf.c
index 13f1010c9..8ff4091e5 100644
--- a/lib/dpif-netdev-perf.c
+++ b/lib/dpif-netdev-perf.c
@@ -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;
@@ -191,25 +192,25 @@  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"
-            "  - 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"
+            "  - 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,
@@ -225,17 +226,16 @@  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);
     }
 }
 
diff --git a/lib/dpif-netdev-unixctl.man b/lib/dpif-netdev-unixctl.man
index ab8619e41..53f33d83f 100644
--- a/lib/dpif-netdev-unixctl.man
+++ b/lib/dpif-netdev-unixctl.man
@@ -123,23 +123,25 @@  Display the last ms_len millisecond stats
 The output always contains the following global PMD statistics:
 .RS
 .IP
-Time: 15:24:55.270 .br
+.EX
+Time: 15:24:55.270
 Measurement duration: 1.008 s
 
 pmd thread numa_id 0 core_id 1:
 
-  Cycles:            2419034712  (2.40 GHz)
-  Iterations:            572817  (1.76 us/it)
-  - idle:                486808  (15.9 % cycles)
-  - busy:                 86009  (84.1 % cycles)
-  Rx packets:           2399607  (2381 Kpps, 848 cycles/pkt)
-  Datapath passes:      3599415  (1.50 passes/pkt)
-  - EMC hits:            336472  ( 9.3 %)
-  - Megaflow hits:      3262943  (90.7 %, 1.00 subtbl lookups/hit)
-  - Upcalls:                  0  ( 0.0 %, 0.0 us/upcall)
-  - Lost upcalls:             0  ( 0.0 %)
-  Tx packets:           2399607  (2381 Kpps)
-  Tx batches:            171400  (14.00 pkts/batch)
+  Iterations:              572817  (1.76 us/it)
+  - Used TSC cycles:   2419034712  ( 99.9 % of total cycles)
+  - idle iterations:       486808  ( 15.9 % of used cycles)
+  - busy iterations:        86009  ( 84.1 % of used cycles)
+  Rx packets:             2399607  (2381 Kpps, 848 cycles/pkt)
+  Datapath passes:        3599415  (1.50 passes/pkt)
+  - EMC hits:              336472  (  9.3 %)
+  - Megaflow hits:        3262943  ( 90.7 %, 1.00 subtbl lookups/hit)
+  - Upcalls:                    0  (  0.0 %, 0.0 us/upcall)
+  - Lost upcalls:               0  (  0.0 %)
+  Tx packets:             2399607  (2381 Kpps)
+  Tx batches:              171400  (14.00 pkts/batch)
+.EE
 .RE
 .IP
 Here "Rx packets" actually reflects the number of packets forwarded by the
diff --git a/manpages.mk b/manpages.mk
index 6ebcf6b70..0fd986e00 100644
--- a/manpages.mk
+++ b/manpages.mk
@@ -255,6 +255,7 @@  vswitchd/ovs-vswitchd.8: \
 	lib/dpif-netdev-unixctl.man \
 	lib/memory-unixctl.man \
 	lib/netdev-dpdk-unixctl.man \
+	lib/ovs.tmac \
 	lib/service.man \
 	lib/ssl-bootstrap.man \
 	lib/ssl-peer-ca-cert.man \
@@ -273,6 +274,7 @@  lib/dpctl.man:
 lib/dpif-netdev-unixctl.man:
 lib/memory-unixctl.man:
 lib/netdev-dpdk-unixctl.man:
+lib/ovs.tmac:
 lib/service.man:
 lib/ssl-bootstrap.man:
 lib/ssl-peer-ca-cert.man:
diff --git a/vswitchd/ovs-vswitchd.8.in b/vswitchd/ovs-vswitchd.8.in
index e39d158d5..901f75e6f 100644
--- a/vswitchd/ovs-vswitchd.8.in
+++ b/vswitchd/ovs-vswitchd.8.in
@@ -1,9 +1,5 @@ 
 .\" -*- nroff -*-
-.de IQ
-.  br
-.  ns
-.  IP "\\$1"
-..
+.so lib/ovs.tmac
 .TH ovs\-vswitchd 8 "@VERSION@" "Open vSwitch" "Open vSwitch Manual"
 .\" This program's name:
 .ds PN ovs\-vswitchd