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Date: Wed, 2 May 2012 13:37:01 +0200
From: Jiri Olsa <jolsa@...hat.com>
To: acme@...hat.com, a.p.zijlstra@...llo.nl, mingo@...e.hu,
paulus@...ba.org, cjashfor@...ux.vnet.ibm.com, fweisbec@...il.com
Cc: eranian@...gle.com, gorcunov@...nvz.org, tzanussi@...il.com,
mhiramat@...hat.com, robert.richter@....com, fche@...hat.com,
linux-kernel@...r.kernel.org, masami.hiramatsu.pt@...achi.com,
drepper@...il.com, asharma@...com
Subject: [RFCv3 00/17] perf: Add backtrace post dwarf unwind
hi,
sending another RFC version. This mainly includes more general
version of perf regs and stack interface. Details are below
and in patches' comments.. ;)
thanks for comments,
jirka
v3 changes:
patch 01/17
- added HAVE_PERF_REGS config option
patch 02/17, 04/17
- regs and stack perf interface is more general now
patch 06/17
- unrelated online fix for i386 compilation
patch 16/17
- few namespace fixies
---
Adding the post unwinding user stack backtrace using dwarf unwind
via libunwind. The original work was done by Frederic. I mostly took
his patches and make them compile in current kernel code plus I added
some stuff here and there.
The main idea is to store user registers and portion of user
stack when the sample data during the record phase. Then during
the report, when the data is presented, perform the actual dwarf
dwarf unwind.
attached patches:
01/17 perf: Unified API to record selective sets of arch registers
02/17 perf: Add ability to attach registers dump to sample
03/17 perf: Factor __output_copy to be usable with specific copy function
04/17 perf: Add ability to attach user stack dump to sample
05/17 perf: Add attribute to filter out user callchains
06/17 perf, tool: Fix format string for x86-32 compilation
07/17 perf, tool: Factor DSO symtab types to generic binary types
08/17 perf, tool: Add interface to read DSO image data
09/17 perf, tool: Add '.note' check into search for NOTE section
10/17 perf, tool: Back [vdso] DSO with real data
11/17 perf, tool: Add interface to arch registers sets
12/17 perf, tool: Add libunwind dependency for dwarf cfi unwinding
13/17 perf, tool: Support user regs and stack in sample parsing
14/17 perf, tool: Support for dwarf cfi unwinding on post processing
15/17 perf, tool: Support for dwarf mode callchain on perf record
16/17 perf, tool: Add dso data caching
17/17 perf, tool: Add dso data caching tests
I tested on Fedora. There was not much gain on i386, because the
binaries are compiled with frame pointers. Thought the dwarf
backtrace is more accurade and unwraps calls in more details
(functions that do not set the frame pointers).
I could see some improvement on x86_64, where I got full backtrace
where current code could got just the first address out of the
instruction pointer.
Example on x86_64:
[dwarf]
perf record -g -e syscalls:sys_enter_write date
100.00% date libc-2.14.90.so [.] __GI___libc_write
|
--- __GI___libc_write
_IO_file_write@@GLIBC_2.2.5
new_do_write
_IO_do_write@@GLIBC_2.2.5
_IO_file_overflow@@GLIBC_2.2.5
0x4022cd
0x401ee6
__libc_start_main
0x4020b9
[frame pointer]
perf record -g fp -e syscalls:sys_enter_write date
100.00% date libc-2.14.90.so [.] __GI___libc_write
|
--- __GI___libc_write
Also I tested on coreutils binaries mainly, but I could see
getting wider backtraces with dwarf unwind for more complex
application like firefox.
The unwind should go throught [vdso] object. I haven't studied
the [vsyscall] yet, so not sure there.
Attached patches should work on both x86 and x86_64. I did
some initial testing so far.
The unwind backtrace can be interrupted by following reasons:
- bug in unwind information of processed shared library
- bug in unwind processing code (most likely ;) )
- insufficient dump stack size
- wrong register value - x86_64 does not store whole
set of registers when in exception, but so far
it looks like RIP and RSP should be enough
thanks for comments,
jirka
---
arch/Kconfig | 6 +
arch/x86/Kconfig | 1 +
arch/x86/include/asm/perf_event.h | 2 +
arch/x86/include/asm/perf_regs.h | 10 +
arch/x86/include/asm/perf_regs_32.h | 84 +++
arch/x86/include/asm/perf_regs_64.h | 99 ++++
include/linux/perf_event.h | 49 ++-
include/linux/perf_regs.h | 28 +
kernel/events/callchain.c | 4 +-
kernel/events/core.c | 204 +++++++-
kernel/events/internal.h | 65 ++-
kernel/events/ring_buffer.c | 4 +-
tools/perf/Makefile | 45 ++-
tools/perf/arch/x86/Makefile | 3 +
tools/perf/arch/x86/include/perf_regs.h | 108 ++++
tools/perf/arch/x86/util/unwind.c | 111 ++++
tools/perf/builtin-record.c | 86 +++-
tools/perf/builtin-report.c | 26 +-
tools/perf/builtin-script.c | 56 ++-
tools/perf/builtin-test.c | 7 +-
tools/perf/builtin-top.c | 7 +-
tools/perf/config/feature-tests.mak | 25 +
tools/perf/perf.h | 9 +-
tools/perf/util/annotate.c | 2 +-
tools/perf/util/dso-test.c | 154 ++++++
tools/perf/util/event.h | 16 +-
tools/perf/util/evlist.c | 24 +
tools/perf/util/evlist.h | 3 +
tools/perf/util/evsel.c | 43 ++-
tools/perf/util/include/linux/compiler.h | 1 +
tools/perf/util/map.c | 23 +-
tools/perf/util/map.h | 7 +-
tools/perf/util/perf_regs.h | 19 +
tools/perf/util/python.c | 3 +-
.../perf/util/scripting-engines/trace-event-perl.c | 3 +-
.../util/scripting-engines/trace-event-python.c | 3 +-
tools/perf/util/session.c | 134 +++++-
tools/perf/util/session.h | 15 +-
tools/perf/util/symbol.c | 435 +++++++++++++---
tools/perf/util/symbol.h | 52 ++-
tools/perf/util/trace-event-scripting.c | 3 +-
tools/perf/util/trace-event.h | 5 +-
tools/perf/util/unwind.c | 565 ++++++++++++++++++++
tools/perf/util/unwind.h | 34 ++
tools/perf/util/vdso.c | 90 +++
tools/perf/util/vdso.h | 8 +
46 files changed, 2488 insertions(+), 193 deletions(-)
--
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