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Date: Mon, 21 May 2012 12:45:20 +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: Re: [RFCv3 00/17] perf: Add backtrace post dwarf unwind hi, any feedback? thanks, jirka On Wed, May 02, 2012 at 01:37:01PM +0200, Jiri Olsa wrote: > 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(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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