iovisor/bcc

Unresolved symbols in profile co-re version

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#5,349 建立於 2025年7月3日

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 (11 留言) (0 反應) (0 負責人)C (22,409 star) (4,051 fork)batch import
bughelp wanted

描述

Hello,

Why does the profile utility from the libbpf-tool return less detailed stack traces compared to the old version?

  • libbpf-tool (10 samples):
$ /opt/bcc/bin/profile -F49 -d --stack-storage-size=$((1024*1024)) -f -p 1087382 10

Could not open /usr/lib/x86_64-linux-gnu/libc.so.6 (deleted)
Could not open /usr/lib/x86_64-linux-gnu/libpthread.so.0 (deleted)
Could not open /usr/lib/x86_64-linux-gnu/libresolv.so.2 (deleted)
Could not open /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 (deleted)
Sampling at 49 Hertz of PID [1087382] by user + kernel for 10 secs.
    [unknown]
    [unknown]
    [unknown]
    [unknown]
    [unknown]
    [unknown]
    -                kubelet (1087382)
        2

    [unknown]
    [unknown]
    [unknown]
    [unknown]
    [unknown]
    -                kubelet (1087382)
...
  • python (154 samples):
$ python3 /opt/bcc/share/bcc/tools/profile -F49 -d --stack-storage-size=$((1024*1024)) -fa -p 1087382 10

Sampling at 49 Hertz of PID [1087382] by user + kernel stack for 10 secs.

    __switch_to+0x165 [kernel]
    __switch_to+0x165 [kernel]
    __schedule+0x2b7 [kernel]
    schedule+0x68 [kernel]
    futex_wait_queue+0x66 [kernel]
    futex_wait+0x151 [kernel]
    do_futex+0x178 [kernel]
    __x64_sys_futex+0x78 [kernel]
    do_syscall_64+0x59 [kernel]
    entry_SYSCALL_64_after_hwframe+0x73 [kernel]
    --
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    [unknown] [kubelet]
    -                kubelet (1087382)
        1
...

Why so huge difference between python based profile and libbpf based versions?

OS: Ubuntu Jammy 22.04 Linux: 6.2.0

貢獻者指南

技術棧
cpython
領域
backendobservabilityperformance
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
half day
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
active
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
mostly clear
前置要求
BCCeBPFLinux profiling
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
40
研究方向
Investigate the symbol resolution code in libbpf tool's profile utility at /src/cc/libbpf tools/profile.c. Compare with the Python version's approach using BCC Python bindings to understand why symbols are unresolved. Look into the comment thread for possible clues about changes in library handling or kernel versions on Ubuntu 22.04 with Linux 6.2.0. The root cause may be missing debug info or incorrect symbol lookup in the new libbpf based version.
Unresolved symbols in profile co-re version · iovisor/bcc#5349 | Good First Issue