Flow eviction and LFT/UFT lifecycle rework#990
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This PR reworks the LFT/UFT lifecycle so that inbound/outbound entries are correctly bound by a single lifetime, and so that a slowpath packet tracks all LFTs which were used in its handling. We then associate this list of LFTs with the flow UFT, and the TCP flow entry if created. This allows us to correctly keep LFTs alive so long as a UFT/TCP entry refers to them. This has been a longstanding bug. The new and really useful feature is that this allows us to remove all related and dependent entries when we deliberately evict an LFT to make space for a new flow. An expiry policy for any table can now also specifiy an "eviction priority" for a given flow. Generally speaking most flows are unevictable so long as they are well-behaved, but the main issue is that we need information from elsewhere to *know* when we can make this determination. How we tackle this is by looking at all descendent flows which rely on a given flow. Most will state no preference on the flow lifecycle, but the TCP flow entry can return a non-zero priority when inactive in a given state for too long. Closes #986. Closes #788. Closes #789.
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From what I can tell this appears to have the same throughput on |
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This PR reworks the LFT/UFT lifecycle so that inbound/outbound entries are correctly bound by a single lifetime, and so that a slowpath packet tracks all LFTs which were used in its handling. We then associate this list of LFTs with the flow UFT, and the TCP flow entry if created.
This allows us to correctly keep LFTs alive so long as a UFT/TCP entry refers to them. This has been a longstanding bug. The new and really useful feature is that this allows us to remove all related and dependent entries when we deliberately evict an LFT to make space for a new flow.
An expiry policy for any table can now also specifiy an "eviction priority" for a given flow. Generally speaking most flows are unevictable so long as they are well-behaved, but the main issue is that we need information from elsewhere to know when we can make this determination. How we tackle this is by looking at all descendent flows which rely on a given flow. Most will state no preference on the flow lifecycle, but the TCP flow entry can return a non-zero priority when inactive in a given state for too long.
Closes #986.
Closes #788.
Closes #789.