Re: [ovs-dev] [PATCH net-next v1 1/1] net: openvswitch: ovs_packet_cmd_execute put sw_flow mainbody in stack

From: Eddy Tao
Date: Sun Feb 19 2023 - 22:44:26 EST


More explanation to the meaning of performance data

>>Mode Iterations   Variance    Average

Iterations: the number of executions of the same test case (each iteration get a performance value of perf[n] )

Average:  sum of all execution and then divided by 'n_iterations'. Below is the pseudo code

               for (sum=0,i=0;i<iterations;i++) sum+= perf[i];

               average = sum/iterations

Variance: A percentage value describing the overall deviation of performance results from average. Below is the pseudo code

               for (deviation=0,i=0;i<iterations;i++) deviation+= square(perf[i] - average);

               variance = ((square_root(deviation/iterations)) * 100)/average


On 2023/2/20 11:04, Eddy Tao wrote:
Hi, Simon:

    To have better visibility of the effect of the patch, i did another test below

Disabling data-path flow installation to steer traffic to slow path only, thus I can observe the performance on slow path, where ovs_packet_cmd_execute is extensively used


Testing topology

            |-----|
      nic1--|     |--nic1
      nic2--|     |--nic2
VM1(16cpus) | ovs |   VM2(16 cpus)
      nic3--|     |--nic3
      nic4--|     |--nic4
            |-----|
2 netperf client threads on each vnic

netperf -H $peer -p $((port+$i)) -t TCP_STREAM  -l 60
netperf -H $peer -p $((port+$i)) -t TCP_RR  -l 60 -- -R 1 -r 120,240
netperf -H $peer -p $((port+$i)) -t TCP_CRR -l 60 -- -R 1 -r 120,240

  Mode Iterations   Variance    Average

TCP_STREAM     10      %3.83       1433 ==> before the change
TCP_STREAM     10      %3.39       1504 ==> after  the change

TCP_RR         10      %2.35      45145 ==> before the change
TCP_RR         10      %1.06      47250 ==> after  the change

TCP_CRR        10      %0.54      11310 ==> before the change
TCP_CRR        10      %2.64      12741 ==> after  the change


Considering the size and simplicity of the patch, i would say the performance benefit is decent.

Thanks

eddy


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