[PATCH] perf report: Fix no libunwind compiled warning break s390 issue

[PATCH] perf report: Fix no libunwind compiled warning break s390 issue

[Jin Yao]

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>
---
 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

Re: [PATCH] perf report: Fix no libunwind compiled warning break s390 issue

[Jiri Olsa]

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..

for the patch:

Acked-by: Jiri Olsa <jolsa@redhat.com>

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
> 

Re: [PATCH] perf report: Fix no libunwind compiled warning break s390 issue

[Jin, Yao]

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
>>
> 

Re: [PATCH] perf report: Fix no libunwind compiled warning break s390 issue

[Jiri Olsa]

On Wed, Jan 08, 2020 at 09:02:02PM +0800, Jin, Yao wrote:
> 
> 
> 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.

ok, that's valid point.. the reason we start discussing it, was that
libunwind does not seem to support compressed ELF debug sections,
which works via libdw unwind

> 
> The command line is as following:
> 
> perf record --call-graph dwarf ./div
> perf report -g graph --stdio

I'll try to do some profiling and check with outr contact in libdw
to comment/check on that

thanks,
jirka

[tip: perf/core] perf report: Fix no libunwind compiled warning break s390 issue

[tip-bot2 for Jin Yao]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     c3314a74f86dc00827e0945c8e5039fc3aebaa3c
Gitweb:        https://git.kernel.org/tip/c3314a74f86dc00827e0945c8e5039fc3aebaa3c
Author:        Jin Yao <yao.jin@linux.intel.com>
AuthorDate:    Wed, 08 Jan 2020 03:17:45 +08:00
Committer:     Arnaldo Carvalho de Melo <acme@redhat.com>
CommitterDate: Tue, 14 Jan 2020 12:02:19 -03:00

perf report: Fix no libunwind compiled warning break s390 issue

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")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Thomas Richter <tmricht@linux.ibm.com>
Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200107191745.18415-1-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 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 627bb65..9483b3f 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