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Differential D56029

hwpmc: improve diagnostic messages for invalid tunables
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Authored by paulo_nlink.com.br on Mar 22 2026, 2:32 PM.
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ali_mashtizadeh.com
mhorne

Details

Reviewers
imp
gnn
ali_mashtizadeh.com
mhorne
Commits
rG290a7adfb1df: hwpmc: improve diagnostic messages for invalid tunables
rGb3a18736ec2f: hwpmc: improve diagnostic messages for invalid tunables
Summary

Replace printf() with log(LOG_WARNING, ...) in pmclog_initialize()
so that tunable validation failures are visible in dmesg and
/var/log/messages rather than only on the early console.

Also improve the messages to report both the invalid value and the
default it resets to, making it easier for users to understand why
their tunable was ignored.

Sponsored by: NLINK (nlink.com.br)

Test Plan

Set kern.hwpmc.nbuffers_pcpu="4096" in /boot/loader.conf.local or
/boot/loader.conf at your flavour.

After reboot, dmesg showed:
hwpmc: nbuffers_pcpu=4096 * logbuffersize=256 exceeds 32MB per CPU
limit, resetting to defaults (32 * 256)

Restored to kern.hwpmc.nbuffers_pcpu="128", clean boot, no warning.
Tested on AMD Ryzen 5600X (Family 19h / Zen 3), FreeBSD 16.0-CURRENT
master-n284614-1ba29614c4ce.

Diff Detail

Repository
rG FreeBSD src repository
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Build Status
Buildable 71655
Build 68538: arc lint + arc unit

Event Timeline

paulo_nlink.com.br created this revision.Mar 22 2026, 2:32 PM
Herald added a reviewer: gnn. · View Herald TranscriptMar 22 2026, 2:32 PM
Herald added a reviewer: ali_mashtizadeh.com. · View Herald Transcript
paulo_nlink.com.br requested review of this revision.Mar 22 2026, 2:32 PM
Harbormaster completed remote builds in B71641: Diff 174116.Mar 22 2026, 2:32 PM
ali_mashtizadeh.com added a comment.Mar 22 2026, 5:09 PM

Might make sense to change these limits to #defines and also you might as well add this information to the man page for hwpmc.

paulo_nlink.com.br updated this revision to Diff 174143.Mar 23 2026, 1:50 AM

Address ali_mashtizadeh.com feedback:

  • Extract hardcoded limits into named #defines in pmc.h: PMC_LOG_BUFFER_SIZE_MAX (16MB) and PMC_NLOGBUFFERS_PCPU_MEM_MAX (32MB)
  • Update log messages to use the new #defines
Harbormaster completed remote builds in B71655: Diff 174143.Mar 23 2026, 1:50 AM
ali_mashtizadeh.com accepted this revision.Mar 23 2026, 3:49 AM
This revision is now accepted and ready to land.Mar 23 2026, 3:49 AM
mhorne accepted this revision.Mar 23 2026, 3:10 PM
mhorne added a subscriber: mhorne.

Thanks. I will commit, with a couple of style/whitespace tweaks.

Closed by commit rGb3a18736ec2f: hwpmc: improve diagnostic messages for invalid tunables (authored by paulo_nlink.com.br, committed by mhorne). · Explain WhyMar 23 2026, 8:22 PM
This revision was automatically updated to reflect the committed changes.
mhorne added a commit: rGb3a18736ec2f: hwpmc: improve diagnostic messages for invalid tunables.
mhorne added a commit: rG290a7adfb1df: hwpmc: improve diagnostic messages for invalid tunables.Apr 16 2026, 3:30 PM

Revision Contents
Changeset List

PathSize
sys/
dev/
hwpmc/
24 lines
sys/
2 lines

Diff 174143

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sys/dev/hwpmc/hwpmc_logging.c

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sys/sys/pmc.h

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