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>
Simplify the historically grown TSC cycle counting in PMD threads.
Cycles are currently counted for the following purposes:
1. Measure PMD ustilization
PMD utilization is defined as ratio of cycles spent in busy iterations
(at least one packet received or sent) over the total number of cycles.
This is already done in pmd_perf_start_iteration() and
pmd_perf_end_iteration() based on a TSC timestamp saved in current
iteration at start_iteration() and the actual TSC at end_iteration().
No dependency on intermediate cycle accounting.
2. Measure the processing load per RX queue
This comprises cycles spend on polling and processing packets received
from the rx queue and the cycles spent on delayed sending of these packets
to tx queues (with time-based batching).
The previous scheme using cycles_count_start(), cycles_count_intermediate()
and cycles-count_end() originally introduced to simplify cycle counting
and saving calls to rte_get_tsc_cycles() was rather obscuring things.
Replace by a nestable cycle_timer with with start and stop functions to
embrace a code segment to be timed. The timed code may contain arbitrary
nested cycle_timers. The duration of nested timers is excluded from the
outer timer.
The caller must ensure that each call to cycle_timer_start() is
followed by a call to cycle_timer_end(). Failure to do so will lead to
assertion failure or a memory leak.
The new cycle_timer is used to measure the processing cycles per rx queue.
This is not yet strictly necessary but will be made use of in a subsequent
commit.
All cycle count functions and data are relocated to module
dpif-netdev-perf.
Signed-off-by: Jan Scheurich <jan.scheurich@ericsson.com>
Acked-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Billy O'Mahony <billy.o.mahony@intel.com>
Signed-off: Ian Stokes <ian.stokes@intel.com>
Add module dpif-netdev-perf to host all PMD performance-related
data structures and functions in dpif-netdev. Refactor the PMD
stats handling in dpif-netdev and delegate whatever possible into
the new module, using clean interfaces to shield dpif-netdev from
the implementation details. Accordingly, the all PMD statistics
members are moved from the main struct dp_netdev_pmd_thread into
a dedicated member of type struct pmd_perf_stats.
Include Darrel's prior refactoring of PMD stats contained in
[PATCH v5,2/3] dpif-netdev: Refactor some pmd stats:
1. The cycles per packet counts are now based on packets
received rather than packet passes through the datapath.
2. Packet counters are now kept for packets received and
packets recirculated. These are kept as separate counters for
maintainability reasons. The cost of incrementing these counters
is negligible. These new counters are also displayed to the user.
3. A display statistic is added for the average number of
datapath passes per packet. This should be useful for user
debugging and understanding of packet processing.
4. The user visible 'miss' counter is used for successful upcalls,
rather than the sum of sucessful and unsuccessful upcalls. Hence,
this becomes what user historically understands by OVS 'miss upcall'.
The user display is annotated to make this clear as well.
5. The user visible 'lost' counter remains as failed upcalls, but
is annotated to make it clear what the meaning is.
6. The enum pmd_stat_type is annotated to make the usage of the
stats counters clear.
7. The subtable lookup stats is renamed to make it clear that it
relates to masked lookups.
8. The PMD stats test is updated to handle the new user stats of
packets received, packets recirculated and average number of datapath
passes per packet.
On top of that introduce a "-pmd <core>" option to the PMD info
commands to filter the output for a single PMD.
Made the pmd-stats-show output a bit more readable by adding a blank
between colon and value.
Signed-off-by: Jan Scheurich <jan.scheurich@ericsson.com>
Co-authored-by: Darrell Ball <dlu998@gmail.com>
Signed-off-by: Darrell Ball <dlu998@gmail.com>
Acked-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Billy O'Mahony <billy.o.mahony@intel.com>
Signed-off: Ian Stokes <ian.stokes@intel.com>
