DellEMC S6100 Enabling Polling Mode for Miim Operation

[sridhar-ravindran]

- What I did
Enabled Polling to verify Miim Operation Completion in S6100
BCM is running in User Mode in Sonic Image. Verifying the Miim Operation completion via interrupt will exhibit performance degradation during high CPU utilization times. We might take more time in handling interrupts. This might lead BCM to declare MIIM timeout.
Moving to MIIM Poller approach will help in mitigating these conditions.

- How I did it
miim_intr_enable = 0
- How to verify it
drivshell>config show miim_intr_enable
config show miim_intr_enable
miim_intr_enable=0

- Description for the changelog

[DellEMC] [S6100] Enabling Polling Mode for Miim Operation

- A picture of a cute animal (not mandatory but encouraged)

[lguohan]

where to define the polling interval?

[sridhar-ravindran]

where to define the polling interval?

Hi Gouhan,

"miim_intr_enable",
"miim_timeout_usec", \

are the only two variables that are user configurable.

miim_timeout_usec is the config variable that is of our interest.

In Master branch , By default it is set to 1 sec.
We do not need more than 1 sec.

drivshell>config show miim_timeout_usec

drivshell>mtim
mtim
MIIM timeout is 1000000 usec

So i did not add this in the code change.

[lguohan]

also what is the average cpu overhead once switch to polling mode?

[lguohan]

what is the average cpu overhead once switch to polling mode?

[sridhar-ravindran]

what is the average cpu overhead once switch to polling mode?

Hi Gouhan,

Please find the average load measured

1. Retrieve syncd utilization every 12 second for 50 iterations
2. 12*50 = 600 seconds(10 minutes)
3. Regular Data Traffic along with 16 BGP sessions.

SYNCD PROCESS UTILIZATION

AVERAGE

                       INTERRUPT     POLLER  
                         =====       ====== 
                        53.136        55.976
                       =======      =====

Attached the text document for detailed Utilisation captures
syncd_poller_profiling.txt