[multi-asic][RFC1213]: Oper status of mgmt interface for multi-asic platform

[SuvarnaMeenakshi]

- What I did
Currently oper status of all management interface is retrieved from STATE DB.
Multi-asic platform does not have any daemon running on the host namespace to update oper status of management interface in STATE DB. This PR is to add a function to retrieve oper status of management interface from kernel file: "/sys/class/net/if_name/operstate".
- How I did it

• Add a new function to retrieve oper status from /sys/class/net/if_name/operstate.
• Invoke this function periodically to retrieve oper status of all management interfaces.
• This is done periodically, instead of retrieving only on SNMP query, so that the time take during the SNMP query does not increase due to the file read operation.
• Add unit-tests for mgmt interface.
  - How to verify it
• Run snmpwalk to get interface status, ensure that the interface status of management interface is correct, on single asic and multi-asic VS testbed.
• With the changes - no impact of single asic platform.
  multi-asic VS testbed:

sudo ifconfig eth0 down
docker exec -it snmp snmpwalk -v2c -c public 127.0.0.1 1.3.6.1.2.1.2.2.1.8
iso.3.6.1.2.1.2.2.1.8.1 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.13 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.17 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.21 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.25 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.29 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1001 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1002 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1003 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1004 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1005 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1006 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5002 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5003 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5012 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5013 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5020 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5021 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5030 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5031 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9000 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9004 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9008 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9012 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9016 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9020 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9024 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9028 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9032 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9036 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9040 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9044 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9048 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9052 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9056 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9060 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9064 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9068 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9072 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9076 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9080 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9084 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9092 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9096 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.10000 = INTEGER: 2 --> status down
sudo ifconfig eth0 up
docker exec -it snmp snmpwalk -v2c -c public 127.0.0.1 1.3.6.1.2.1.2.2.1.8
iso.3.6.1.2.1.2.2.1.8.1 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.13 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.17 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.21 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.25 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.29 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1001 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1002 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1003 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1004 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1005 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.1006 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5002 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5003 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5012 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5013 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5020 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5021 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5030 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.5031 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9000 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9004 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9008 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9012 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9016 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9020 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9024 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9028 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9032 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9036 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9040 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9044 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9048 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9052 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9056 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9060 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9064 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9068 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9072 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9076 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.8.9080 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9084 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9092 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.9096 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.8.10000 = INTEGER: 1 --> status up

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[abdosi]

@SuvarnaMeenakshi Regarding this:

This is done periodically, instead of retrieving only on SNMP query, so that the time take during the SNMP query does not increase due to the file read operation.

Have we seen slowness if we do only during SNMP walk ? I am wondering doing parodically results makes system more slow compare to only doing when needed especially if walk is not that common operation.

[SuvarnaMeenakshi]

@SuvarnaMeenakshi Regarding this:

This is done periodically, instead of retrieving only on SNMP query, so that the time take during the SNMP query does not increase due to the file read operation.

Have we seen slowness if we do only during SNMP walk ? I am wondering doing parodically results makes system more slow compare to only doing when needed especially if walk is not that common operation.
To check this , I did comparison of running time of _get_if_entry_state_db() which is invoked upon SNMP query and update_data() which is invoked periodically. The running time was obtained before the changes in this PR and after calling _get_mgmt_oper_status() in either functions. I ran the SNMP walk to get operstatus of all interfaces 100 times on a multi-asic DUT to get average running time over 100 cycles, and update_data which is called periodically, was also calculated over 100 cycles. With that, below are the time taken:
Without this change: _get_if_entry_state_db time taken 1.3980865478515625e-05 seconds
After this change:
_get_if_entry_state_db time taken 5.311250686645508e-05. seconds
Without this change: update_data time taken 0.0767834734916687 seconds
After this change: update_data time taken 0.07709113597869872 seconds

As update_data time does not show as much increase as see in _get_if_entry_state_db(), decided to keep in update_data.

[qiluo-msft]

Could you help explore another solution: run a process portsyncd in the host namespace, it will update oper status of management interface in STATE DB. The benefit simplified responsibilities of daemon and telemetry services. Let's say sonic-telemetry would like to get the same data, no need to poll there.