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Diffstat (limited to 'lib/dpif-netdev-unixctl.man')
-rw-r--r-- | lib/dpif-netdev-unixctl.man | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/lib/dpif-netdev-unixctl.man b/lib/dpif-netdev-unixctl.man index 76c3e4efa..ab8619e41 100644 --- a/lib/dpif-netdev-unixctl.man +++ b/lib/dpif-netdev-unixctl.man @@ -149,6 +149,65 @@ 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-perf-log-set\fR \fBon\fR|\fBoff\fR \ +[\fB-b\fR \fIbefore\fR] [\fB-a\fR \fIafter\fR] [\fB-e\fR|\fB-ne\fR] \ +[\fB-us\fR \fIusec\fR] [\fB-q\fR \fIqlen\fR]" +. +The userspace "netdev" datapath is able to supervise the PMD performance +metrics and detect iterations with suspicious statistics according to the +following criteria: +.RS +.IP \(em +The iteration lasts longer than \fIusec\fR microseconds (default 250). +This can be used to capture events where a PMD is blocked or interrupted for +such a period of time that there is a risk for dropped packets on any of its Rx +queues. +.IP \(em +The max vhost qlen exceeds a threshold \fIqlen\fR (default 128). This can be +used to infer virtio queue overruns and dropped packets inside a VM, which are +not visible in OVS otherwise. +.RE +.IP +Such suspicious iterations can be logged together with their iteration +statistics in the \fBovs-vswitchd.log\fR to be able to correlate them to +packet drop or other events outside OVS. + +The above command enables (\fBon\fR) or disables (\fBoff\fR) supervision and +logging at run-time and can be used to adjust the above thresholds for +detecting suspicious iterations. By default supervision and logging is +disabled. + +The command options are: +.RS +.IP "\fB-b\fR \fIbefore\fR" +The number of iterations before the suspicious iteration to be logged +(default 5). +.IP "\fB-a\fR \fIafter\fR" +The number of iterations after the suspicious iteration to be logged +(default 5). +.IP "\fB-e\fR" +Extend logging interval if another suspicious iteration is detected +before logging occurs. +.IP "\fB-ne\fR" +Do not extend logging interval if another suspicious iteration is detected +before logging occurs (default). +.IP "\fB-q\fR \fIqlen\fR" +Suspicious vhost queue fill level threshold. Increase this to 512 if the Qemu +supports 1024 virtio queue length (default 128). +.IP "\fB-us\fR \fIusec\fR" +Change the duration threshold for a suspicious iteration (default 250 us). +.RE + +Note: Logging of suspicious iterations itself consumes a considerable amount +of processing cycles of a PMD which may be visible in the iteration history. +In the worst case this can lead OVS to detect another suspicious iteration +caused by logging. + +If more than 100 iterations around a suspicious iteration have been logged +once, OVS falls back to the safe default values (-b 5 -a 5 -ne) to avoid +that logging itself continuously causes logging of further suspicious +iterations. +. .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. |