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3f86fdf5ce
This commit adds a new command to retrieve the list of available DPIF implementations. This can be used by to check what implementations of the DPIF are available in any given OVS binary. It also returns which implementations are in use by the OVS PMD threads. Usage: $ ovs-appctl dpif-netdev/dpif-impl-get Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com> Co-authored-by: Cian Ferriter <cian.ferriter@intel.com> Signed-off-by: Cian Ferriter <cian.ferriter@intel.com> Acked-by: Flavio Leitner <fbl@sysclose.org> Signed-off-by: Ian Stokes <ian.stokes@intel.com>
235 lines
7.8 KiB
Groff
235 lines
7.8 KiB
Groff
.SS "DPIF-NETDEV COMMANDS"
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These commands are used to expose internal information (mostly statistics)
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about the "dpif-netdev" userspace datapath. If there is only one datapath
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(as is often the case, unless \fBdpctl/\fR commands are used), the \fIdp\fR
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argument can be omitted. By default the commands present data for all pmd
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threads in the datapath. By specifying the "-pmd Core" option one can filter
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the output for a single pmd in the datapath.
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.
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.IP "\fBdpif-netdev/pmd-stats-show\fR [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
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Shows performance statistics for one or all pmd threads of the datapath
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\fIdp\fR. The special thread "main" sums up the statistics of every non pmd
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thread.
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The sum of "emc hits", "smc hits", "megaflow hits" and "miss" is the number of
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packet lookups performed by the datapath. Beware that a recirculated packet
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experiences one additional lookup per recirculation, so there may be
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more lookups than forwarded packets in the datapath.
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Cycles are counted using the TSC or similar facilities (when available on
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the platform). The duration of one cycle depends on the processing platform.
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"idle cycles" refers to cycles spent in PMD iterations not forwarding any
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any packets. "processing cycles" refers to cycles spent in PMD iterations
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forwarding at least one packet, including the cost for polling, processing and
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transmitting said packets.
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To reset these counters use \fBdpif-netdev/pmd-stats-clear\fR.
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.
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.IP "\fBdpif-netdev/pmd-stats-clear\fR [\fIdp\fR]"
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Resets to zero the per pmd thread performance numbers shown by the
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\fBdpif-netdev/pmd-stats-show\fR and \fBdpif-netdev/pmd-perf-show\fR commands.
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It will NOT reset datapath or bridge statistics, only the values shown by
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the above commands.
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.
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.IP "\fBdpif-netdev/pmd-perf-show\fR [\fB-nh\fR] [\fB-it\fR \fIiter_len\fR] \
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[\fB-ms\fR \fIms_len\fR] [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
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Shows detailed performance metrics for one or all pmds threads of the
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user space datapath.
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The collection of detailed statistics can be controlled by a new
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configuration parameter "other_config:pmd-perf-metrics". By default it
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is disabled. The run-time overhead, when enabled, is in the order of 1%.
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.RS
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.IP
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.PD .4v
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.IP \(em
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used cycles
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.IP \(em
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forwared packets
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.IP \(em
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number of rx batches
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.IP \(em
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packets/rx batch
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.IP \(em
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max. vhostuser queue fill level
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.IP \(em
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number of upcalls
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.IP \(em
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cycles spent in upcalls
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.PD
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.RE
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.IP
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This raw recorded data is used threefold:
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.RS
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.IP
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.PD .4v
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.IP 1.
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In histograms for each of the following metrics:
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.RS
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.IP \(em
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cycles/iteration (logarithmic)
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.IP \(em
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packets/iteration (logarithmic)
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.IP \(em
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cycles/packet
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.IP \(em
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packets/batch
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.IP \(em
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max. vhostuser qlen (logarithmic)
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.IP \(em
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upcalls
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.IP \(em
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cycles/upcall (logarithmic)
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The histograms bins are divided linear or logarithmic.
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.RE
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.IP 2.
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A cyclic history of the above metrics for 1024 iterations
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.IP 3.
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A cyclic history of the cummulative/average values per millisecond wall
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clock for the last 1024 milliseconds:
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.RS
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.IP \(em
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number of iterations
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.IP \(em
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avg. cycles/iteration
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.IP \(em
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packets (Kpps)
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.IP \(em
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avg. packets/batch
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.IP \(em
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avg. max vhost qlen
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.IP \(em
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upcalls
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.IP \(em
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avg. cycles/upcall
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.RE
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.PD
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.RE
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.IP
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.
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The command options are:
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.RS
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.IP "\fB-nh\fR"
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Suppress the histograms
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.IP "\fB-it\fR \fIiter_len\fR"
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Display the last iter_len iteration stats
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.IP "\fB-ms\fR \fIms_len\fR"
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Display the last ms_len millisecond stats
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.RE
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.IP
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The output always contains the following global PMD statistics:
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.RS
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.IP
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.EX
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Time: 15:24:55.270
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Measurement duration: 1.008 s
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pmd thread numa_id 0 core_id 1:
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Iterations: 572817 (1.76 us/it)
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- Used TSC cycles: 2419034712 ( 99.9 % of total cycles)
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- idle iterations: 486808 ( 15.9 % of used cycles)
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- busy iterations: 86009 ( 84.1 % of used cycles)
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Rx packets: 2399607 (2381 Kpps, 848 cycles/pkt)
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Datapath passes: 3599415 (1.50 passes/pkt)
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- EMC hits: 336472 ( 9.3 %)
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- SMC hits: 0 ( 0.0 %)
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- Megaflow hits: 3262943 ( 90.7 %, 1.00 subtbl lookups/hit)
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- Upcalls: 0 ( 0.0 %, 0.0 us/upcall)
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- Lost upcalls: 0 ( 0.0 %)
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Tx packets: 2399607 (2381 Kpps)
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Tx batches: 171400 (14.00 pkts/batch)
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.EE
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.RE
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.IP
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Here "Rx packets" actually reflects the number of packets forwarded by the
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datapath. "Datapath passes" matches the number of packet lookups as
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reported by the \fBdpif-netdev/pmd-stats-show\fR command.
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To reset the counters and start a new measurement use
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\fBdpif-netdev/pmd-stats-clear\fR.
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.
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.IP "\fBdpif-netdev/pmd-perf-log-set\fR \fBon\fR|\fBoff\fR \
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[\fB-b\fR \fIbefore\fR] [\fB-a\fR \fIafter\fR] [\fB-e\fR|\fB-ne\fR] \
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[\fB-us\fR \fIusec\fR] [\fB-q\fR \fIqlen\fR]"
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.
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The userspace "netdev" datapath is able to supervise the PMD performance
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metrics and detect iterations with suspicious statistics according to the
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following criteria:
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.RS
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.IP \(em
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The iteration lasts longer than \fIusec\fR microseconds (default 250).
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This can be used to capture events where a PMD is blocked or interrupted for
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such a period of time that there is a risk for dropped packets on any of its Rx
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queues.
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.IP \(em
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The max vhost qlen exceeds a threshold \fIqlen\fR (default 128). This can be
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used to infer virtio queue overruns and dropped packets inside a VM, which are
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not visible in OVS otherwise.
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.RE
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.IP
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Such suspicious iterations can be logged together with their iteration
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statistics in the \fBovs-vswitchd.log\fR to be able to correlate them to
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packet drop or other events outside OVS.
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The above command enables (\fBon\fR) or disables (\fBoff\fR) supervision and
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logging at run-time and can be used to adjust the above thresholds for
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detecting suspicious iterations. By default supervision and logging is
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disabled.
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The command options are:
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.RS
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.IP "\fB-b\fR \fIbefore\fR"
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The number of iterations before the suspicious iteration to be logged
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(default 5).
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.IP "\fB-a\fR \fIafter\fR"
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The number of iterations after the suspicious iteration to be logged
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(default 5).
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.IP "\fB-e\fR"
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Extend logging interval if another suspicious iteration is detected
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before logging occurs.
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.IP "\fB-ne\fR"
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Do not extend logging interval if another suspicious iteration is detected
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before logging occurs (default).
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.IP "\fB-q\fR \fIqlen\fR"
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Suspicious vhost queue fill level threshold. Increase this to 512 if the Qemu
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supports 1024 virtio queue length (default 128).
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.IP "\fB-us\fR \fIusec\fR"
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Change the duration threshold for a suspicious iteration (default 250 us).
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.RE
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Note: Logging of suspicious iterations itself consumes a considerable amount
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of processing cycles of a PMD which may be visible in the iteration history.
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In the worst case this can lead OVS to detect another suspicious iteration
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caused by logging.
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If more than 100 iterations around a suspicious iteration have been logged
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once, OVS falls back to the safe default values (-b 5 -a 5 -ne) to avoid
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that logging itself continuously causes logging of further suspicious
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iterations.
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.
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.IP "\fBdpif-netdev/pmd-rxq-show\fR [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
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For one or all pmd threads of the datapath \fIdp\fR show the list of queue-ids
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with port names, which this thread polls.
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.
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.IP "\fBdpif-netdev/pmd-rxq-rebalance\fR [\fIdp\fR]"
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Reassigns rxqs to pmds in the datapath \fIdp\fR based on their current usage.
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.
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.IP "\fBdpif-netdev/bond-show\fR [\fIdp\fR]"
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When "other_config:lb-output-action" is set to "true", the userspace datapath
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handles the load balancing of bonds directly instead of depending on flow
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recirculation (only in balance-tcp mode).
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When this is the case, the above command prints the load-balancing information
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of the bonds configured in datapath \fIdp\fR showing the interface associated
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with each bucket (hash).
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.
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.IP "\fBdpif-netdev/dpif-impl-get\fR
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Lists the DPIF implementations that are available.
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.
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.IP "\fBdpif-netdev/dpif-impl-set\fR \fIdpif_impl\fR"
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Sets the DPIF to be used to \fIdpif_impl\fR. By default "dpif_scalar" is used.
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