namhyung.kim at lge
May 20, 2012, 11:00 PM
Post #4 of 6
Re: [RFC 0/5] perf tools: Minimalistic build without libelf dependency
[In reply to]
Any other comments for this?
On Mon, 14 May 2012 16:10:19 +0900, Namhyung Kim wrote:
> NOTE: This is a RFC patchset and it contains a lot of rough edges
> and ugly codes.
> Current build procedure of perf tools requires a couple of external
> libraries. Although most of them are optional, elfutils' libelf is
> mandatory for resolving symbols and build-id of the binaries being
> profiled. For some reason, it makes embedded guys' life harder who
> want to build and run perf tools on their boards.
> This patch set tries to fix the problem by letting the perf could
> be built without libelf. The initial intent was just providing
> perf record command to gather performance events interested on the
> system and copies the data to development box to be used by perf
> report for analysis.
> However it's changed to have most of perf commands as is because
> perf can resolve kernel symbols without libelf and many of perf
> commands deal (mostly) with kernel events - so no need to restrict
> capability of perf tools. Therefore, the end result is not so
> minimalistic in fact and only thing it cannot do is "perf probe".
> And then I realized that the perf record needs to know about the
> build-id's anyway :(. So I implemented a poor man's version of elf
> parser only for parsing the build-id info.
> To build a minimal perf tools, pass MINIMAL=1 to make. The perf
> report will not display symbol names:
> # Samples: 988 of event 'cycles'
> # Event count (approx.): 3726465542
> # Overhead Command Shared Object Symbol
> # ........ ....... ................. .........................
> 98.40% noploop noploop [.] 0x000000000000066d
> 1.35% noploop ld-2.15.so [.] 0x000000000000bab1
> 0.10% noploop [kernel.kallsyms] [k] native_write_msr_safe
> 0.10% noploop [kernel.kallsyms] [k] scheduler_tick
> 0.03% noploop [kernel.kallsyms] [k] bad_range
> 0.01% noploop [kernel.kallsyms] [k] pipe_read
> But perf buildid-list can show you the build-id's:
> $ ./perf buildid-list
> ebfc1bdb98999c64d36ddfe394c58df3de6cbcfb [kernel.kallsyms]
> 52f0c5f25b95075e6fd7682763f7c3a779a4e889 /usr/lib64/ld-2.15.so
> 43a7a2b399b6ee2ff29c6bdadbda6bff88712ed4 /home/namhyung/bin/noploop
> So it can be packed using perf archive so copied and analized
> with full-fledged perf tools on a development machine.
> This patchset is based on commit cb04ff9ac424 ("sched, perf: Use
> a single callback into the scheduler") and tested on x86_64 and arm.
> Any comments are welcome, thanks.
> Namhyung Kim (5):
> perf symbols: Introduce symbol__elf_init()
> perf symbols: Do not use ELF's symbol binding constants
> perf tools: Split out util/symbol-elf.c
> perf tools: Support minimal build
> perf symbols: Implement poor man's ELF parser
> tools/perf/Makefile | 29 ++
> tools/perf/builtin-buildid-list.c | 4 +-
> tools/perf/builtin-top.c | 5 +-
> tools/perf/command-list.txt | 2 +-
> tools/perf/perf.c | 2 +
> tools/perf/ui/browsers/map.c | 5 +-
> tools/perf/util/elf-minimal.h | 153 ++++++++
> tools/perf/util/generate-cmdlist.sh | 15 +
> tools/perf/util/symbol-elf.c | 691 +++++++++++++++++++++++++++++++++
> tools/perf/util/symbol-minimal.c | 258 +++++++++++++
> tools/perf/util/symbol.c | 712 ++---------------------------------
> tools/perf/util/symbol.h | 20 +
> 12 files changed, 1195 insertions(+), 701 deletions(-)
> create mode 100644 tools/perf/util/elf-minimal.h
> create mode 100644 tools/perf/util/symbol-elf.c
> create mode 100644 tools/perf/util/symbol-minimal.c
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