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net: collect LLE cache statistics
Needs ReviewPublic

Authored by kevans on Oct 7 2021, 7:41 AM.

Details

Reviewers
melifaro
Group Reviewers
network
NetApp
Summary

Track cache lookup/hits. A future commit will export these for display
in arp(8).

Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
X-NetApp-PR: #66

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint OK
Unit
No Unit Test Coverage
Build Status
Buildable 41998
Build 38886: arc lint + arc unit

Event Timeline

kevans requested review of this revision.Oct 7 2021, 7:41 AM

Would it be possible to describe a use case for the feature?

sys/net/if_ethersubr.c
326

If we really want the data, can we avoid atomics here and use counter(9) instead?

sys/net/if_llatbl.h
91

struct llentry fields are specifically ordered in the way that all fields used by the fast path are in the first cache line.

sys/netinet/in.c
1581

If we really want the data, can we avoid atomics here and use counter(9) instead?

Would it be possible to describe a use case for the feature?

NetApp uses it downstream for validation and testing -- we could stash it off behind a config option if you'd feel better about that?

Would it be possible to describe a use case for the feature?

NetApp uses it downstream for validation and testing -- we could stash it off behind a config option if you'd feel better about that?

I have some changes related to linking nhops with llentries, so the datapath avoids looking up / referencing llentries for routes with gateway. Per-lle counters may be a bit hard to support in that scenario.
Are other methods of getting the counters (dtrace, ipfw counters) out of the table?