[Reclaiming buffer][202106] Support reclaiming buffer in traditional model

[stephenxs]

What I did
It's to port #2011 to 202106
To reclaim reserved buffer.
As the way to do it differs among vendors, buffermgrd will:

• Handle port admin down on Mellanox platform.
  • Not apply lossless buffer PG to an admin-down port
  • Remove lossless buffer PG (3-4) from a port when it is shut down.
• Readd lossless buffer PG (3-4) to a port when a port is started up.

Signed-off-by: Stephen Sun [email protected]

Why I did it
To support reclaiming reserved buffer when a port is shut down on Mellanox platform in traditional buffer model.

How I verified it

Regression test and vs test.

Details if related

[stephenxs]

/azpw run

[mssonicbld]

/AzurePipelines run

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[stephenxs]

/azpw run

[mssonicbld]

/AzurePipelines run

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[stephenxs]

It can be cherry-picked to 202012 branch (commit e37302d) cleanly, so tag added.

[stephenxs]

/azpw run

[mssonicbld]

/AzurePipelines run

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[neethajohn]

@prsunny , do we do such kind of cherry-picks? from non master branch?

[prsunny]

agree with Neetha. typically we don't follow this model. if it cannot be cherry-picked from master, please raise separate PRs to release branches.

[stephenxs]

agree with Neetha. typically we don't follow this model. if it cannot be cherry-picked from master, please raise separate PRs to release branches.

Thanks for clarifying it. Will open another PR for 202012. Thanks.

[stephenxs]

agree with Neetha. typically we don't follow this model. if it cannot be cherry-picked from master, please raise separate PRs to release branches.

Thanks for clarifying it. Will open another PR for 202012. Thanks.

PR #2063 created for 202012.

[qiluo-msft]

/azp run

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[liat-grozovik]

/azp run Azure.sonic-swss

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[liat-grozovik]

/azp run

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[stephenxs]

Currently, the PR depends on #2118 for the vstest failure.

[liat-grozovik]

/azp run Azure.sonic-swss

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Azure Pipelines successfully started running 1 pipeline(s).