[sflow]: backport psample and act_sample drivers, needed for sonic-vs platform

[rakeshdatta]

• What I did

Backport psample and act_sample drivers to sonic linux kernel 4.9.

• How I did it

Both psample and act_sample are needed for sflow feature.

psample driver is needed for collecting samples from the interfaces at the kernel level.
act_sample driver is needed for the 'tc' command to be able to program the sampling configurations into the interfaces at the kernel level.

psample and act_sample drivers are not back-ported yet to the linux kernel version that sonic-linux-kernel is using. Hence, I have taken the patches for both the drivers and included it in our sonic kernel.

• How to verify it

  • Using Build infrastructure changes to support sflow docker and utilities sonic-buildimage#3251 changes, build a sonic image
    This step would include the psample and act_sample drivers into the sonic-linux-kernel.
    Also, it would install the psample.ko and act_sample.ko in a sonic-vs target at the start-up time.

  • Using sonic-utilities: Add support for sFlow sonic-utilities#592 changes, use the CLIs to configure sflow globally and on a port.

  • Thereafter, use the show CLI to verify the config changes made.

  • Pump traffic into the port where sampling is configured.

  • Kernel would generate NETLINK messages, containing the packet samples, and send them to the hsflowd daemon. At hsflowd side, we would be able to see the incoming packet samples.

• Description for the changelog

  • Update: Added psample driver into the sonic kernel, which enables
    packet sampling in the vs environment
  • Update: Added act_sample driver into the sonic kernel, which enables 'sample' action
    for the 'tc' command

Signed-off-by: Rakesh Datta [email protected]

[prsunny]

@marian-pritsak to review