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doc: add some features to DLB2 guide

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Add queue depth threshold and class of service sections
to DLB2 rst file.

Fixes: 5433956 ("event/dlb2: add eventdev probe")

Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>
This commit is contained in:
Timothy McDaniel 2020-11-05 15:22:51 -06:00 committed by Jerin Jacob
parent 47dc89fefa
commit 95aa7101cd
1 changed files with 46 additions and 0 deletions
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46
doc/guides/eventdevs/dlb2.rst
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@ -363,3 +363,49 @@ increase a vdev's per-queue atomic-inflight allocation to (for example) 64:
--vdev=dlb1_event,atm_inflights=64
QID Depth Threshold
~~~~~~~~~~~~~~~~~~~
DLB2 supports setting and tracking queue depth thresholds. Hardware uses
the thresholds to track how full a queue is compared to its threshold.
Four buckets are used
- Less than or equal to 50% of queue depth threshold
- Greater than 50%, but less than or equal to 75% of depth threshold
- Greater than 75%, but less than or equal to 100% of depth threshold
- Greater than 100% of depth thresholds
Per queue threshold metrics are tracked in the DLB2 xstats, and are also
returned in the impl_opaque field of each received event.
The per qid threshold can be specified as part of the device args, and
can be applied to all queue, a range of queues, or a single queue, as
shown below.
.. code-block:: console
--vdev=dlb2_event,qid_depth_thresh=all:<threshold_value>
--vdev=dlb2_event,qid_depth_thresh=qidA-qidB:<threshold_value>
--vdev=dlb2_event,qid_depth_thresh=qid:<threshold_value>
Class of service
~~~~~~~~~~~~~~~~
DLB2 supports provisioning the DLB2 bandwidth into 4 classes of service.
- Class 4 corresponds to 40% of the DLB2 hardware bandwidth
- Class 3 corresponds to 30% of the DLB2 hardware bandwidth
- Class 2 corresponds to 20% of the DLB2 hardware bandwidth
- Class 1 corresponds to 10% of the DLB2 hardware bandwidth
- Class 0 corresponds to don't care
The classes are applied globally to the set of ports contained in this
scheduling domain, which is more appropriate for the bifurcated
PMD than for the PF PMD, since the PF PMD supports just 1 scheduling
domain.
Class of service can be specified in the devargs, as follows
.. code-block:: console
--vdev=dlb2_event,cos=<0..4>