Few hints:

1. When you observe “show run” statistics, you always do:

1. start traffic
2. clear run
3. wait a bit
4 show run

Otherwise statistics will show you average which includes period without 
traffic.


2. debug CLI commands are typically causing barrier sync (unless handler is 
explicitly marked as thread safe),
and that can stop worker threads for more than 500 usec. In such situations it 
is normal and expected that you will observe
small amount of rx tail drops as simply worker is not servicing specific NIC 
queue for significant amount of time.


> On 26 Mar 2019, at 04:04, Chandra Mohan, Vijay Mohan <[email protected]> 
> wrote:
> 
> Hi Everyone,
>  
> I am working on measuring the performance with a xconnect of two 
> sub-interfaces. I did see quite a few performance related questions & answers 
> in the community which were very helpful to get to this point. However, I’m 
> still facing rx and tx queue drops (“rx misses” and “tx-error”). 
>  
> Here is the config :
> l2 xconnect TenGigabitEthernet3/0/0.1 TenGigabitEthernet3/0/1.1
> l2 xconnect TenGigabitEthernet3/0/1.1 TenGigabitEthernet3/0/0.1
>  
> I’m passing traffic which is 70% of the line rate (10G) in both directions 
> and I do not see any drops. Ran the traffic for 30 Min with no drops. Below 
> is the runtime stats. Have CPU affinity in place and “vpp_wk_0” is on 
> dedicated logical core 9. However, I see that the “vectors/node” is 26.03 . I 
> was expecting to see 255.99. Is it something that can be seen only with high 
> burst of traffic ?  I may be missing something here and looking to understand 
> what that may be.
> Thread 1 vpp_wk_0 (lcore 9)
> Time 531.8, average vectors/node 26.03, last 128 main loops 1.31 per node 
> 21.00
>   vector rates in 1.1539e6, out 1.1539e6, drop 0.0000e0, punt 0.0000e0
>              Name                 State         Calls          Vectors        
> Suspends         Clocks       Vectors/Call 
> TenGigabitEthernet3/0/0-output   active           18857661       306865019    
>            0          1.54e2           16.27
> TenGigabitEthernet3/0/0-tx       active           18857661       306865019    
>            0          2.62e2           16.27
> TenGigabitEthernet3/0/1-output   active           18857661       306865172    
>            0          1.63e2           16.27
> TenGigabitEthernet3/0/1-tx       active           18857661       306865172    
>            0          2.67e2           16.27
> dpdk-input                       polling          18857661       613730191    
>            0          4.48e2           32.55
> ethernet-input                   active           18864470       613730191    
>            0          6.92e2           32.53
> l2-input                         active           18864470       613730191    
>            0          1.15e2           32.53
> l2-output                        active           18864470       613730191    
>            0          1.31e2           32.53
>  
> There are two rx-queues and two tx-queues assigned to each of the 10 Gig 
> ports. Queue depth is 1024. Following is the queue placement:
> Thread 1 (vpp_wk_0):
>   node dpdk-input:
>     TenGigabitEthernet3/0/0 queue 0 (polling)
>     TenGigabitEthernet3/0/0 queue 1 (polling)
>     TenGigabitEthernet3/0/1 queue 0 (polling)
>     TenGigabitEthernet3/0/1 queue 1 (polling)
>  
> Now, when I increase the rate to 75% of 10G, I am seeing drops due to 
> “rx-miss”
> DBGvpp# sho int     
>               Name               Idx    State  MTU (L3/IP4/IP6/MPLS)     
> Counter          Count    
> TenGigabitEthernet3/0/0           1      up          9000/0/0/0     rx 
> packets              26235935
>                                                                     rx bytes  
>            39248958760
>                                                                     tx 
> packets              26236104
>                                                                     tx bytes  
>            39249211584
>                                                                     rx-miss   
>                    697
> TenGigabitEthernet3/0/0.1         3      up           0/0/0/0       rx 
> packets              26235935
>                                                                     rx bytes  
>            39248958760
>                                                                     tx 
> packets              26236104
>                                                                     tx bytes  
>            39249211584
> TenGigabitEthernet3/0/1           2      up          9000/0/0/0     rx 
> packets              26236104
>                                                                     rx bytes  
>            39249211584
>                                                                     tx 
> packets              26235935
>                                                                     tx bytes  
>            39248958760
>                                                                     rx-miss   
>                    711
> TenGigabitEthernet3/0/1.1         4      up           0/0/0/0       rx 
> packets              26236104
>                                                                     rx bytes  
>            39249211584
>                                                                     tx 
> packets              26235935
>                                                                     tx bytes  
>            39248958760
> local0                            0     down          0/0/0/0    
>  
> Here is the runtime stats when that happens:
> Thread 1 vpp_wk_0 (lcore 9)
> Time 59.0, average vectors/node 34.58, last 128 main loops 1.69 per node 27.00
>   vector rates in 1.2365e6, out 1.2365e6, drop 0.0000e0, punt 0.0000e0
>              Name                 State         Calls          Vectors        
> Suspends         Clocks       Vectors/Call 
> TenGigabitEthernet3/0/0-output   active            1682608        36482575    
>            0          1.33e2           21.68
> TenGigabitEthernet3/0/0-tx       active            1682608        36482575    
>            0          2.48e2           21.68
> TenGigabitEthernet3/0/1-output   active            1682608        36482560    
>            0          1.42e2           21.68
> TenGigabitEthernet3/0/1-tx       active            1682608        36482560    
>            0          2.53e2           21.68
> dpdk-input                       polling           1682608        72965135    
>            0          4.11e2           43.36
> ethernet-input                   active            1691495        72965135    
>            0          6.77e2           43.14
> l2-input                         active            1691495        72965135    
>            0          1.08e2           43.14
> l2-output                        active            1691495        72965135    
>            0          1.07e2           43.14
>  
> Would increasing the core, threads be of any help ? or Given that vector/node 
> is 34.58, does it mean there is still room to process more frames ?
>  
> Also, there are two Rx queues configured. Is there a command to check if they 
> are equally serviced ? looking to understand how the load is equally 
> distributed over the two rx-queues and two tx queues.
>  
> Any help to determine why this drop might be happening will be great.
>  
>  
> Thanks,
> Vijay
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