metrics: fix overhead_program_seconds_total unit (ns -> s)

[danilovid]

The metric tetragon_overhead_program_seconds_total was incorrectly storing
nanoseconds (raw RunTimeNs from BPF program stats) despite the _seconds_total
naming convention.

The root cause was an early conversion of time.Duration to uint64 in
ProgOverhead.RunTime, which lost the type context. Following the Prometheus
convention, time.Duration is now kept throughout and converted to seconds
only when collecting metrics using m.Seconds().

Fixes #4829

Description

Keep time.Duration in ProgOverhead.RunTime instead of converting to uint64,
and use m.Seconds() when reporting to Prometheus.

Changelog

Fix `tetragon_overhead_program_seconds_total` metric to correctly report seconds instead of nanoseconds

[FedeDP]

Nice catch!

[mtardy]

Could you show us what the metric now typically looks now? thanks

[danilovid]

Could you show us what the metric now typically looks now? thanks

Here's what the metric looks like currently - Grafana shows ~4 hours per BPF program call.

Here is the current state of the panel in Grafana.

[mtardy]

Could you show us what the metric now typically looks now? thanks

Here's what the metric looks like currently - Grafana shows ~4 hours per BPF program call.

ah sorry I was unclear I meant after this patch, the typical output in the HTTP reply, I just wanted to make sure there's no rounding or so, it should be 10-9/10-8 numbers I imagine.

[danilovid]

Could you show us what the metric now typically looks now? thanks

Here's what the metric looks like currently - Grafana shows ~4 hours per BPF program call.

ah sorry I was unclear I meant after this patch, the typical output in the HTTP reply, I just wanted to make sure there's no rounding or so, it should be 10-9/10-8 numbers I imagine.

After the patch, the metric values look correct:

tetragon_overhead_program_seconds_total{attach="wake_up_new_task",...} 0.003527708
tetragon_overhead_program_runs_total{attach="wake_up_new_task",...} 249

Average: 0.003527708 / 249 = ~14 µs per call - which is a realistic value for a BPF program.

Before the patch the same metric would show values like 3527708 (nanoseconds reported as seconds).

[mtardy]

It looks like it's almost there you just need to fix checkpatch complaints, mostly commit title length and sign off missing:

=========================================================
[1/1] Running on b66f2b4ebf5d6ebe1efed863484126aeb4ae2922
metrics: fix overhead_program_seconds_total to report seconds instead of nanoseconds
=========================================================
Error: ERROR:MISSING_SIGN_OFF: Missing Signed-off-by: line(s)


NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

"[PATCH] metrics: fix overhead_program_seconds_total to report seconds" has style problems, please review.

NOTE: Ignored message types: AVOID_EXTERNS BIT_MACRO C99_COMMENTS C99_COMMENT_TOLERANCE COMMIT_LOG_LONG_LINE COMMIT_MESSAGE COMPLEX_MACRO CONSTANT_CONVERSION CONST_STRUCT EMAIL_SUBJECT ENOSYS FILE_PATH_CHANGES FROM_SIGN_OFF_MISMATCH GIT_COMMIT_ID JIFFIES_COMPARISON LEADING_SPACE LONG_LINE LONG_LINE_COMMENT LONG_LINE_STRING MACRO_ARG_REUSE MACRO_WITH_FLOW_CONTROL MULTISTATEMENT_MACRO_USE_DO_WHILE NOT_UNIFIED_DIFF OPEN_ENDED_LINE PREFER_DEFINED_ATTRIBUTE_MACRO PREFER_KERNEL_TYPES PRINTK_WITHOUT_KERN_LEVEL REPEATED_WORD SPDX_LICENSE_TAG TRACE_PRINTK TRAILING_SEMICOLON TRAILING_STATEMENTS VOLATILE

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.
Error: ERROR:CUSTOM: Please avoid long commit subjects (max: 75, found: 84)

On sign-off

To improve tracking of who did what, the Tetragon project uses a "sign-off" procedure which you can learn more about in the Cilium project documentation.

Concretely it consists of adding your real name and an email address to your git config and using git commit -s to write your commit message. You can use git commit --amend -s to add the signature to existing commits.

See more details on how to comply with the "sign-off" procedure

To add your name and email to your git config:

git config user.email "mail@example.com"
git config user.name "firstname lastname"

Note: add the --global flag after config to configure this by default for repositories on your host.

Then you can use for new commits:

git commit -s

Or for existing commits on which you want to add the signed-off-by statement:

git commit --amend -s

For more information, see this extract from git-commit(1) man page regarding the -s flag:

-s, --signoff, --no-signoff
   Add a Signed-off-by trailer by the committer at the end of the commit log
   message. The meaning of a signoff depends on the project to which you're
   committing. For example, it may certify that the committer has the rights to
   submit the work under the project's license or agrees to some contributor
   representation, such as a Developer Certificate of Origin. (See
   http://developercertificate.org for the one used by the Linux kernel and Git
   projects.) Consult the documentation or leadership of the project to which
   you're contributing to understand how the signoffs are used in that project.

   The --no-signoff option can be used to countermand an earlier --signoff
   option on the command line.

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[olsajiri]

thanks