On Mon, 28 Oct 2024 16:27:41 +0200 Viacheslav Ovsiienko <viachesl...@nvidia.com> wrote:
> The mlx5 provides the scheduling send on time capability. > The check the operating status of this feature the xstats > counters are provided. This patch adds the counter descriptions > and provides some meaningful information how to interpret > the counter values in runtime. > > Signed-off-by: Viacheslav Ovsiienko <viachesl...@nvidia.com> > --- > doc/guides/nics/mlx5.rst | 48 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 48 insertions(+) > > diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst > index f82e2d75de..8d1a1311d4 100644 > --- a/doc/guides/nics/mlx5.rst > +++ b/doc/guides/nics/mlx5.rst > @@ -2655,3 +2655,51 @@ Destroy GENEVE TLV parser for specific port:: > > This command doesn't destroy the global list, > For releasing options, ``flush`` command should be used. > + > + > +Extended statistics counters > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +Send scheduling related xstats counters > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +The mlx5 PMD provides the set of tx_pp feature related counters to provide > debug and diagnostics > +on send packet scheduling. These counters are applicable only if port was > probed with ``tx_pp`` > +devarg and reflect the status of PMD scheduling infrastructure based on > Clock and Rearm Queues. > +This infrastructure provedies the Send Scheduling capability on CX6DX NICs > as temporary workaround > +and should not be engaged on the newer hardware. > + > +- ``tx_pp_missed_interrupt_errors`` - the Rearm Queue interrupt was not > serviced in time. EAL handles > + interrupts in dedicated thread and, possible, there were another > time-consuming actions were taken. > + > +- ``tx_pp_rearm_queue_errors`` - hardware errors occurred on Rearm Queue, > usually it is caused by not > + servicing interrupts in time > + > +- ``tx_pp_clock_queue_errors`` - hardware errors occurred on Clock Queue, > usually it indicates some > + configuration or internal NIC hardware or firmware issues > + > +- ``tx_pp_timestamp_past_errors`` - application tried to send packet(s) with > specifying timestamp in the past. > + This counter is useful to check and debug the application code, it does > not indicate PMD malfunction. > + > +- ``tx_pp_timestamp_future_errors`` - application tried to send packet(s) > with specifying timestamp > + in the too distant future, beyond the hardware capabilities to schedule > the sending > + This counter is useful to check and debug the application code, it does > not indicate PMD malfunction. > + > +- ``tx_pp_jitter`` - this counter exposes the internal NIC realtime clock > jitter estimation between two > + neighbour Clock Queue completions in nanoseconds. Significant jitter might > alert about clock > + synchronization issues (say, some system PTP agent might adjust NIC clock > in inappropriate way) > + > +- ``tx_pp_wander`` - the counter exposes the longterm internal NUC realtime > clock stability - tx_pp_wander > + for 2^24 completions, in nanoseconds. Significant wander might indicate > clock synchronization issues. > + > +- ``tx_pp_sync_lost`` - the general operating indicator, the non-zero value > says the driver lost > + the Clock Queue synchronization and scheduling does not operate correctly. > The port must be restarted > + to restore the correct scheduling functioning. > + > +The following counters are extremely useful for application code check and > debug, these ones do not > +indicate driver or hardware mulfunctions, and are also applicable for the > newer hardware (with direct > +on time scheduling capabilities - ConnectX-7 and above): > + > +- ``tx_pp_timestamp_order_errors`` - application tried to send packet(s) > with timestamps in not > + strictly ascending order. Because of PMD does not reorder packets in the > hardware queues, scheduling > + timestamps order violation causes sending packets in wrong moments of time. Lots of grammar and spelling errors and overly wordy. Please spend some time cleaning up the wording, find a writer or AI tool to help.
