Re: [PATCH 0/2] perf: we can now read separate debug-info files based on a build ID

From: Dima Kogan
Date: Wed Sep 16 2015 - 14:50:18 EST


Hi. This is a gentle ping. This patch fixes a real bug, and it'd be
great if it was merged.

Here's a demo. This is on a recent Debian/sid box, tracing malloc()
calls in emacs. The debug symbols for libc and emacs are split into
separate (installed) packages, as is the norm.

$ perf probe -x /lib/x86_64-linux-gnu/libc-2.19.so --add malloc

$ perf record -g -eprobe_libc:malloc -p `pidof emacs`

Before patch:

$ perf script | head -n 10
emacs 7750 [001] 353845.297868: probe_libc:malloc: (7f4fbde59020)
7c020 malloc (/lib/x86_64-linux-gnu/libc-2.19.so)
144877 [unknown] (/usr/bin/emacs-snapshot-lucid)
144989 [unknown] (/usr/bin/emacs-snapshot-lucid)
144bcc [unknown] (/usr/bin/emacs-snapshot-lucid)
15a91b [unknown] (/usr/bin/emacs-snapshot-lucid)
99f25 [unknown] (/usr/bin/emacs-snapshot-lucid)
199211 [unknown] (/usr/bin/emacs-snapshot-lucid)
1a0c6b [unknown] (/usr/bin/emacs-snapshot-lucid)
1ed86 [unknown] (/usr/bin/emacs-snapshot-lucid)

After patch:

$ perf script | head -n 10
emacs 7750 [001] 353845.297868: probe_libc:malloc: (7f4fbde59020)
7c020 malloc (/lib/x86_64-linux-gnu/libc-2.19.so)
144877 allocate_string_data (/usr/bin/emacs-snapshot-lucid)
144989 make_uninit_multibyte_string (/usr/bin/emacs-snapshot-lucid)
144bcc make_uninit_string.part.18 (/usr/bin/emacs-snapshot-lucid)
15a91b make_buffer_string_both (/usr/bin/emacs-snapshot-lucid)
99f25 decode_coding_object (/usr/bin/emacs-snapshot-lucid)
199211 read_process_output (/usr/bin/emacs-snapshot-lucid)
1a0c6b wait_reading_process_output (/usr/bin/emacs-snapshot-lucid)
1ed86 sit_for (/usr/bin/emacs-snapshot-lucid)
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