Add Digest extern to PSA/eBPF backend #3164
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Co-authored-by: Mateusz Kossakowski <mateusz.kossakowski@orange.com> Co-authored-by: Jan Palimąka <jan.palimaka@orange.com>
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| Digests are intended to carry a small piece of user-defined data from the data plane to a control plane. | ||
| The PSA-eBPF compiler translates each Digest instance into `BPF_MAP_TYPE_QUEUE` that implements a FIFO queue. | ||
| If a deparser triggers the `pack()` method, an eBPF program inserts data defined for a Digest into the BPF queue map using `bpf_map_push_elem`. |
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perhaps you can add a link to the relevant section in the psa specification
| ### Digest | ||
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| Digests are intended to carry a small piece of user-defined data from the data plane to a control plane. | ||
| The PSA-eBPF compiler translates each Digest instance into `BPF_MAP_TYPE_QUEUE` that implements a FIFO queue. |
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I guess you have a separate table to keep them strongly typed, instead of one table with a union?
This will lose the relative ordering of digests between different tables.
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For a single Digest instance, there is a separate BPF map of type BPF_MAP_TYPE_QUEUE. No unions, etc. Just a straightforward mapping.
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There is no requirement in PSA that data plane -> controller ordering must be maintained across different instances of Digest externs.
backends/ebpf/psa/ebpfPsaGen.cpp
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| this->visit(p4Control->body); | ||
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| return false; | ||
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| void ConvertToEBPFDeparserPSA::findDigests(const IR::P4Control *p4Control) { | ||
| // Digests are only at ingress |
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That's why you should probably give an error if you find one in egress.
I would check this later.
Also, perhaps this field should not be called "type"; we already have many types.
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@mbudiu-vmw what about this one? I've addressed/answered your review. |
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As you can see, lately I have a lot of reviews to do, so I appreciate if you actively tell me when you are done. |
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Got it and understood, I'll be pinging you when I'm done with addressing a review! |
This PR adds support for Digest extern to PSA/eBPF backend.
Digests are implemented using
BPF_MAP_TYPE_QUEUE. An eBPF program generates a Digest by callingbpf_map_push_elem. A user space application can get a Digest by callingpsabpf-ctl digest get pipeorbpf_map_lookup_and_delete_elemC API.This is another PR from series implementing PSA support for eBPF backend.