On 16/12/2021 15:49, Pai G, Sunil wrote:
Hi Kevin ,
Couple of minor nits below.
@@ -240,29 +240,29 @@ PMD Automatic Load Balance (experimental)
-----------------------------------------
-Cycle or utilization based allocation of Rx queues to PMDs gives efficient -
load distribution but it is not adaptive to change in traffic pattern -occurring
over the time. This may cause an uneven load among the PMDs which -
results in overall lower throughput.
+Cycle or utilization based allocation of Rx queues to PMDs is done to
+give an efficient load distribution based at the time of assignment.
+However, over time it may become less efficient due to to changes in
Two "to" above.
+traffic. This may cause an uneven load among the PMDs, which in the
+worst case may result in packet drops and lower throughput.
-To address this automatic load balancing of PMDs can be set by::
+To address this, automatic load balancing of PMDs can be enabled by::
$ ovs-vsctl set open_vswitch . other_config:pmd-auto-lb="true"
-The following conditions need to be met to have Auto Load balancing
-enabled:
+The following are minimum configuration pre-requisites needed for PMD
+Auto Load Balancing to operate:
-1. cycle or group based assignment of RX queues to PMD is enabled.
-2. pmd-auto-lb is set to true.
+1. ``pmd-auto-lb`` is enabled.
+2. ``cycle`` (default) or ``group`` based Rx queue assignment is selected.
3. There are two or more non-isolated PMDs present.
-4. And at least one of the non-isolated PMD has more than one queue
polling.
+4. At least one non-isolated PMD is polling more than one Rx queue.
-If any of above is not met PMD Auto Load Balancing is disabled.
+When PMD Auto Load Balance is enabled, a PMD core's percentage CPU
+utilization processing packets is measured. The PMD is considered above
+the threshold if that percentage utilization is greater than the load
+threshold every 10 secs for 1 minute.
I wonder if we could use the term 'overloaded' instead of 'above the threshold'
?
Don't have a strong preference tbh.
I tried to avoid using 'overloaded' here because it might suggest that
the CPU is at 100% utilization processing packets, and the datapath is
in some error state where packets are dropping etc.
For example, if the user sets the threshold for 70% and the cycles are
above it at say 80% and all working well, it might be confusing to call
that 'overloaded'. So I tried to just reference the threshold itself
e.g. 'above the threshold'. WDYT?
<snipped>
Rest LGTM
Thanks for the reviews,
Kevin.
Thanks and regards,
Sunil
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