Messages in this thread | | | Subject | Re: [PATCH] perf report: Fix no libunwind compiled warning break s390 issue | From | "Jin, Yao" <> | Date | Wed, 8 Jan 2020 21:02:02 +0800 |
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On 1/8/2020 6:27 PM, Jiri Olsa wrote: > On Wed, Jan 08, 2020 at 03:17:45AM +0800, Jin Yao wrote: >> Commit 800d3f561659 ("perf report: Add warning when libunwind not compiled in") >> breaks the s390 platform. S390 uses libdw-dwarf-unwind for call chain >> unwinding and had no support for libunwind. >> >> So the warning "Please install libunwind development packages during the perf build." >> caused the confusion even if the call-graph is displayed correctly. >> >> This patch adds checking for HAVE_DWARF_SUPPORT, which is set when >> libdw-dwarf-unwind is compiled in. >> >> Fixes: 800d3f561659 ("perf report: Add warning when libunwind not compiled in") >> >> Reviewed-by: Thomas Richter <tmricht@linux.ibm.com> >> Tested-by: Thomas Richter <tmricht@linux.ibm.com> >> Signed-off-by: Jin Yao <yao.jin@linux.intel.com> > > perfect, I have the same change prepared for sending, but it's > together with making libdw default dwarf unwinder, which I'm still > not sure we want to do, so it all got posponed ;-) > > would you guys be ok with that? with having libdw picked up as default dwarf unwinder.. >
I've roughly compared the performance between libunwind-dev and libdw-dev. While in my test (on KBL desktop), for the same perf report command-line, it looks the perf built with libunwind-dev is much faster than the perf built with libdw-dev.
The command line is as following:
perf record --call-graph dwarf ./div perf report -g graph --stdio
Maybe you give it a try. :)
> for the patch: > > Acked-by: Jiri Olsa <jolsa@redhat.com> > Thanks for reviewing the patch.
Thanks Jin Yao
> thanks, > jirka > >> --- >> tools/perf/builtin-report.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c >> index de988589d99b..66cd97cc8b92 100644 >> --- a/tools/perf/builtin-report.c >> +++ b/tools/perf/builtin-report.c >> @@ -412,10 +412,10 @@ static int report__setup_sample_type(struct report *rep) >> PERF_SAMPLE_BRANCH_ANY)) >> rep->nonany_branch_mode = true; >> >> -#ifndef HAVE_LIBUNWIND_SUPPORT >> +#if !defined(HAVE_LIBUNWIND_SUPPORT) && !defined(HAVE_DWARF_SUPPORT) >> if (dwarf_callchain_users) { >> - ui__warning("Please install libunwind development packages " >> - "during the perf build.\n"); >> + ui__warning("Please install libunwind or libdw " >> + "development packages during the perf build.\n"); >> } >> #endif >> >> -- >> 2.17.1 >> >
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