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Gmane
From: Akihiro Nagai <akihiro.nagai.hw <at> hitachi.com>
Subject: [PATCH -tip v3 0/6] perf: Introduce branch sub commands
Newsgroups: gmane.linux.kernel
Date: Thursday 24th March 2011 11:31:37 UTC (over 5 years ago)
Hi,

This patch series provides the commands 'perf branch record' and 'perf
branch trace'
version 3. These commands record and analyze a BTS (Branch Trace Store)
log.
And, they provide the interface to use BTS log for application developers.

BTS is a facility of Intel x86 processors, which records the address of
'branch to/from' on every branch/jump instruction and interrupt.
This facility is very useful for developers to test their software,
for example, coverage test, execution path analysis, dynamic step count
...etc.
These test tools have a big advantage, which user doesn't have to modify
target
executable binaries, because the BTS is a hardware feauture.

But, there are few applications using BTS. Reasons I guess are ...
 - Few people know what BTS is.
 - Few people know how to use BTS on Linux box.
 - It's hard to analyze the BTS log because it includes just a series of
addresses.

So, I want to provide a user-friendly interface to BTS for application
developers.


 About new sub commands
========================
'perf branch record' provides an easy way to record BTS log.
Usage is 'perf branch record '.  This command is just an alias to
'perf record -e branches:u -c 1 '. But, new one is more simple and
more intuitive.

'perf branch trace' can parse and analyze recorded BTS log and print
various
information of execution path. This command can show address, pid, command
name,
function+offset, file path of elf.
You can choose the printed information with option.

Example: 'perf branch trace'
function+offset
irq_return+0x0  => _start+0x0
irq_return+0x0  => _start+0x0
_start+0x3      => _dl_start+0x0
irq_return+0x0  => _dl_start+0x0
irq_return+0x0  => _dl_start+0x26
irq_return+0x0  => _dl_start+0x2d
_dl_start+0x71  => _dl_start+0x93
_dl_start+0x97  => _dl_start+0x78
...

This is the default behavior of 'perf branch trace'. It prints
function+offset.


Example2: 'perf branch -cas trace'
command address            function+offset                  
ls      0xffffffff8146fe0e irq_return+0x0  => ls   0x0000003806200b20
_start+0x0
ls      0xffffffff8146fe0e irq_return+0x0  => ls   0x0000003806200b20
_start+0x0
ls      0x0000003806200b23 _start+0x3      => ls   0x0000003806204910
_dl_start+0x0
ls      0xffffffff8146fe0e irq_return+0x0  => ls   0x0000003806204910
_dl_start+0x0
ls      0xffffffff8146fe0e irq_return+0x0  => ls   0x0000003806204936
_dl_start+0x26
ls      0xffffffff8146fe0e irq_return+0x0  => ls   0x000000380620493d
_dl_start+0x2d
ls      0x0000003806204981 _dl_start+0x71  => ls   0x00000038062049a3
_dl_start+0x93
ls      0x00000038062049a7 _dl_start+0x97  => ls   0x0000003806204988
_dl_start+0x78
...

In the future, I'd like to make this more informative. For example
 - Show source file path
 - Show line number
 - Show inlined function name
 - Draw call graph
 - Browse source code and coloring
 - Make BTS record fast
and more!

Changes in V3:
 - Update to the latest -tip tree
 - Rename to 'perf branch'
 - Process only BTS records
 - Fix bug of getting elf_filepath
 - Fix return value of __cmd_trace

Changes in V2:
 - Update to the latest -tip tree
 - Add bts explanation to the subcommand list
 - Remove the patch already merged (add OPT_CALLBACK_DEFAULT_NOOPT)
 - Add comments
 - Add new function to the todo list

Thanks,

---

Akihiro Nagai (6):
      perf branch trace: add print all option
      perf branch trace: print function+offset
      perf branch trace: print file path of the executed elf
      perf branch trace: print pid and command
      perf branch: Introduce new sub command 'perf branch trace'
      perf: new subcommand perf branch record


 tools/perf/Documentation/perf-branch.txt |   54 +++++
 tools/perf/Makefile                      |    1 
 tools/perf/builtin-branch.c              |  329
++++++++++++++++++++++++++++++
 tools/perf/builtin.h                     |    1 
 tools/perf/command-list.txt              |    1 
 tools/perf/perf.c                        |    1 
 6 files changed, 387 insertions(+), 0 deletions(-)
 create mode 100644 tools/perf/Documentation/perf-branch.txt
 create mode 100644 tools/perf/builtin-branch.c

-- 
Akihiro Nagai ([email protected])
 
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