oracle / oracle/dtrace

tracing failed with error "failed to create BPF map 'aggs': Too big"

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Dominant language
C
Stars
189
Forks
23
PR merge metrics
No merged PRs in 30d

Description

I was trying a simple oneliner from the dtrace book on a Linux box and got this:

# dtrace -n 'syscall:::entry { @sc[execname, probefunc] = count(); }'                                                                                    
dtrace: description 'syscall:::entry ' matched 325 probes                             
dtrace: could not enable tracing: failed to create BPF map 'aggs': Too big  
# rpm -q dtrace                                                     
dtrace-2.0.1-1.el9.x86_64

This is on a custom Linux kernel 5.10 on AlmaLinux 9. I haven't tried reproducing the problem on a newer kernel. I will do so when I get a chance and report back.

Contributor guide

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the DTrace one-liner shown in the issue on the reported Linux 5.10 kernel, then compare its behavior with a newer kernel as suggested. Investigate the BPF map-size failure and determine whether it is caused by the kernel environment or DTrace; done means the cause and a viable fix or limitation are established.

Written by the indexing model from the issue text.

Assessment

Tech stack
linux
Domain
observability-sre, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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