iflib: Make txq mp ring stats persistent
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Authored by zlei on Sep 22 2024, 5:13 PM.

Details

Reviewers

jhb
erj
shurd

Group Reviewers

iflib

Summary

Those stats get reset on every iflib_stop(), e.g., ifconfig em0 -tso.
However it is harmless if they persist. Currenty they are retrived only
via sysctl. A upcoming fix will make use of drops to correctly report
output dropped packets of an interface. With this change we will not
have to save the drops stat on every iflib_stop(), then the code will
be simpler.

MFC after: 2 weeks

Test Plan

Verify the txq mp ring stats persist after changing interface flags.

# sysctl dev.igc.0 | grep txq | grep enqueues
dev.igc.0.iflib.txq3.r_enqueues: 0
dev.igc.0.iflib.txq2.r_enqueues: 0
dev.igc.0.iflib.txq1.r_enqueues: 0
dev.igc.0.iflib.txq0.r_enqueues: 4

# ifconfig igc0 -tso
# sysctl dev.igc.0 | grep txq | grep enqueues
dev.igc.0.iflib.txq3.r_enqueues: 0
dev.igc.0.iflib.txq2.r_enqueues: 0
dev.igc.0.iflib.txq1.r_enqueues: 0
dev.igc.0.iflib.txq0.r_enqueues: 4

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rG FreeBSD src repository

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Event Timeline

zlei created this revision.Sep 22 2024, 5:13 PM

Herald added a reviewer: shurd. · View Herald TranscriptSep 22 2024, 5:13 PM

Herald added 1 blocking reviewer(s): iflib. · View Herald Transcript

Herald added subscribers: glebius, melifaro, ae, imp. · View Herald Transcript

zlei requested review of this revision.Sep 22 2024, 5:13 PM

zlei mentioned this in D46186: iflib: Add iflib managed counters support.Sep 22 2024, 5:17 PM

zlei added a child revision: D46186: iflib: Add iflib managed counters support.

For what it's worth I think the TSO reset is due to ifnet, iflib, and individual drivers only making various decisions during attach that would better be done in helper functions that are called during init and SIOCSIFCAP and not some real limitation of the network stack or hardware. It would be cool to not need that reset. I left a more relevant comment in https://reviews.freebsd.org/D46186#inline-280367

zlei mentioned this in D46187: Use iflib_if_get_counter_default() to get output dropped packets.Sep 25 2024, 10:10 AM

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sys/

net/

iflib.c

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iflib: Make txq mp ring stats persistentNeeds ReviewPublicActions