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dpif-netdev: Detailed performance stats for PMDs

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This patch instruments the dpif-netdev datapath to record detailed
statistics of what is happening in every iteration of a PMD thread.

The collection of detailed statistics can be controlled by a new
Open_vSwitch configuration parameter "other_config:pmd-perf-metrics".
By default it is disabled. The run-time overhead, when enabled, is
in the order of 1%.

The covered metrics per iteration are:
  - cycles
  - packets
  - (rx) batches
  - packets/batch
  - max. vhostuser qlen
  - upcalls
  - cycles spent in upcalls

This raw recorded data is used threefold:

1. In histograms for each of the following metrics:
   - cycles/iteration (log.)
   - packets/iteration (log.)
   - cycles/packet
   - packets/batch
   - max. vhostuser qlen (log.)
   - upcalls
   - cycles/upcall (log)
   The histograms bins are divided linear or logarithmic.

2. A cyclic history of the above statistics for 999 iterations

3. A cyclic history of the cummulative/average values per millisecond
   wall clock for the last 1000 milliseconds:
   - number of iterations
   - avg. cycles/iteration
   - packets (Kpps)
   - avg. packets/batch
   - avg. max vhost qlen
   - upcalls
   - avg. cycles/upcall

The gathered performance metrics can be printed at any time with the
new CLI command

ovs-appctl dpif-netdev/pmd-perf-show [-nh] [-it iter_len] [-ms ms_len]
    [-pmd core] [dp]

The options are

-nh:            Suppress the histograms
-it iter_len:   Display the last iter_len iteration stats
-ms ms_len:     Display the last ms_len millisecond stats
-pmd core:      Display only the specified PMD

The performance statistics are reset with the existing
dpif-netdev/pmd-stats-clear command.

The output always contains the following global PMD statistics,
similar to the pmd-stats-show command:

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)

Signed-off-by: Jan Scheurich <jan.scheurich@ericsson.com>
Acked-by: Billy O'Mahony <billy.o.mahony@intel.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>
This commit is contained in:
Jan Scheurich
2018-04-19 19:40:45 +02:00
committed by Ian Stokes
parent 8492adc270
commit 79f368756c
9 changed files with 990 additions and 68 deletions
Download Patch File Download Diff File Expand all files Collapse all files

157
lib/dpif-netdev-unixctl.man Normal file
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.SS "DPIF-NETDEV COMMANDS"
These commands are used to expose internal information (mostly statistics)
about the "dpif-netdev" userspace datapath. If there is only one datapath
(as is often the case, unless \fBdpctl/\fR commands are used), the \fIdp\fR
argument can be omitted. By default the commands present data for all pmd
threads in the datapath. By specifying the "-pmd Core" option one can filter
the output for a single pmd in the datapath.
.
.IP "\fBdpif-netdev/pmd-stats-show\fR [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
Shows performance statistics for one or all pmd threads of the datapath
\fIdp\fR. The special thread "main" sums up the statistics of every non pmd
thread.
The sum of "emc hits", "masked hits" and "miss" is the number of
packet lookups performed by the datapath. Beware that a recirculated packet
experiences one additional lookup per recirculation, so there may be
more lookups than forwarded packets in the datapath.
Cycles are counted using the TSC or similar facilities (when available on
the platform). The duration of one cycle depends on the processing platform.
"idle cycles" refers to cycles spent in PMD iterations not forwarding any
any packets. "processing cycles" refers to cycles spent in PMD iterations
forwarding at least one packet, including the cost for polling, processing and
transmitting said packets.
To reset these counters use \fBdpif-netdev/pmd-stats-clear\fR.
.
.IP "\fBdpif-netdev/pmd-stats-clear\fR [\fIdp\fR]"
Resets to zero the per pmd thread performance numbers shown by the
\fBdpif-netdev/pmd-stats-show\fR and \fBdpif-netdev/pmd-perf-show\fR commands.
It will NOT reset datapath or bridge statistics, only the values shown by
the above commands.
.
.IP "\fBdpif-netdev/pmd-perf-show\fR [\fB-nh\fR] [\fB-it\fR \fIiter_len\fR] \
[\fB-ms\fR \fIms_len\fR] [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
Shows detailed performance metrics for one or all pmds threads of the
user space datapath.
The collection of detailed statistics can be controlled by a new
configuration parameter "other_config:pmd-perf-metrics". By default it
is disabled. The run-time overhead, when enabled, is in the order of 1%.
.RS
.IP
.PD .4v
.IP \(em
used cycles
.IP \(em
forwared packets
.IP \(em
number of rx batches
.IP \(em
packets/rx batch
.IP \(em
max. vhostuser queue fill level
.IP \(em
number of upcalls
.IP \(em
cycles spent in upcalls
.PD
.RE
.IP
This raw recorded data is used threefold:
.RS
.IP
.PD .4v
.IP 1.
In histograms for each of the following metrics:
.RS
.IP \(em
cycles/iteration (logarithmic)
.IP \(em
packets/iteration (logarithmic)
.IP \(em
cycles/packet
.IP \(em
packets/batch
.IP \(em
max. vhostuser qlen (logarithmic)
.IP \(em
upcalls
.IP \(em
cycles/upcall (logarithmic)
The histograms bins are divided linear or logarithmic.
.RE
.IP 2.
A cyclic history of the above metrics for 1024 iterations
.IP 3.
A cyclic history of the cummulative/average values per millisecond wall
clock for the last 1024 milliseconds:
.RS
.IP \(em
number of iterations
.IP \(em
avg. cycles/iteration
.IP \(em
packets (Kpps)
.IP \(em
avg. packets/batch
.IP \(em
avg. max vhost qlen
.IP \(em
upcalls
.IP \(em
avg. cycles/upcall
.RE
.PD
.RE
.IP
.
The command options are:
.RS
.IP "\fB-nh\fR"
Suppress the histograms
.IP "\fB-it\fR \fIiter_len\fR"
Display the last iter_len iteration stats
.IP "\fB-ms\fR \fIms_len\fR"
Display the last ms_len millisecond stats
.RE
.IP
The output always contains the following global PMD statistics:
.RS
.IP
Time: 15:24:55.270 .br
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)
.RE
.IP
Here "Rx packets" actually reflects the number of packets forwarded by the
datapath. "Datapath passes" matches the number of packet lookups as
reported by the \fBdpif-netdev/pmd-stats-show\fR command.
To reset the counters and start a new measurement use
\fBdpif-netdev/pmd-stats-clear\fR.
.
.IP "\fBdpif-netdev/pmd-rxq-show\fR [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
For one or all pmd threads of the datapath \fIdp\fR show the list of queue-ids
with port names, which this thread polls.
.
.IP "\fBdpif-netdev/pmd-rxq-rebalance\fR [\fIdp\fR]"
Reassigns rxqs to pmds in the datapath \fIdp\fR based on their current usage.