iovisor/bcc

Unresolved symbols in profile co-re version

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#5,349 opened on 2025年7月3日

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bughelp wanted

説明

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

コントリビューターガイド

技術スタック
cpython
領域
backendobservabilityperformance
Issue 種別
bug
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
3
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
half day
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
active
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
mostly clear
前提条件
BCCeBPFLinux profiling
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
40
調査方針
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.