openzfs/zfs

arc_summary to be able to show only altered tunables,spl

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#11,685 opened on Mar 3, 2021

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Type: Featuregood first issue

Description

Describe the feature would like to see added to OpenZFS

arc_summary -s tunables/spl currently shows all values I wish I was able to quickly see only the modified values. By passing a new supplementary argument, arc_summary would omit showing tunables that are left at their default values

How will this feature improve OpenZFS?

Easier and faster identification of alterations in arc_summary tunables section output

Additional context

to help arc_summary automate obtaining default values instead of hardcoding them, modinfo -p for zfs,spl,icp and zcommon should also display default values, not just the description, in a parsable form (an identifiable pattern to extract the default value)

Contributor guide

Tech stack
cpython
Domain
cliperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Python knowledgeUnderstanding of arc summaryFamiliarity with ZFS tunables
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue requests a new flag for arc summary to show only non default tunables. A maintainer suggested using modinfo p to get defaults (see issue #11686). The implementation should modify the arc summary Python script to compare current values with defaults. Key files to review: cmd/arc summary. The script currently lists all tunables; adding logic to filter by default values requires parsing modinfo output or hardcoding defaults. The linked issue #11686 proposes enhancing modinfo to include defaults. Focus on implementing the flag and integrating with modinfo.
arc_summary to be able to show only altered tunables,spl · openzfs/zfs#11685 | Good First Issue