Re: [PATCH 23/24] perf buildid-list: Add support for mmap2's buildid events

From: Arnaldo Carvalho de Melo
Date: Tue Nov 17 2020 - 12:54:06 EST

Em Tue, Nov 17, 2020 at 04:21:40PM +0100, Jiri Olsa escreveu:
> On Tue, Nov 17, 2020 at 09:50:40AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Tue, Nov 17, 2020 at 12:00:52PM +0100, Jiri Olsa escreveu:
> > > Add buildid-list support for mmap2's build id data, so we can
> > > display build ids for dso objects for data without the build
> > > id cache update.
> >
> > > $ perf buildid-list
> > > 1805c738c8f3ec0f47b7ea09080c28f34d18a82b /usr/lib64/ld-2.31.so
> > > d278249792061c6b74d1693ca59513be1def13f2 /usr/lib64/libc-2.31.so
> > >
> > > By default only dso objects with hits are shown.
> >
> > Would be interesting to be able to show all the build ids that are
> > there. a 'perf buildid-list --all' or make this under --force?
>
> ok, will check.. one other tool I think would be handy is
> to show which debuginfo is not available, because it can
> change the report a lot - missing symbols are not getting
> accounted, and their hits are accounted only as separated
> addresses

Right, as below.

So you suggest something like:

# perf buildid-cache --fetch-missing-debuginfo

?

- Arnaldo

[root@quaco ~]# rpm -qf `which stress-ng`
stress-ng-0.11.21-1.fc32.x86_64
[root@quaco ~]# rpm -q stress-ng-debuginfo
stress-ng-debuginfo-0.07.29-10.fc31.x86_64
[root@quaco ~]# perf record stress-ng -t 1 -c 1
stress-ng: info: [656926] dispatching hogs: 1 cpu
stress-ng: info: [656926] successful run completed in 1.02s
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.204 MB perf.data (4082 samples) ]
[root@quaco ~]# perf report | head -20
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 4K of event 'cycles'
# Event count (approx.): 3997318603
#
# Overhead Command Shared Object Symbol
# ........ ............. ................ ..............................
#
7.91% stress-ng-cpu stress-ng [.] 0x0000000000035ed9
7.15% stress-ng-cpu stress-ng [.] 0x0000000000035ecc
6.54% stress-ng-cpu stress-ng [.] 0x000000000003bbf6
4.39% stress-ng-cpu stress-ng [.] 0x000000000003a083
4.15% stress-ng-cpu stress-ng [.] 0x0000000000065ed8
3.67% stress-ng-cpu stress-ng [.] 0x0000000000065ecf
3.41% stress-ng-cpu stress-ng [.] 0x0000000000065ee1
3.11% stress-ng-cpu stress-ng [.] 0x000000000003bbf2
2.65% stress-ng-cpu stress-ng [.] 0x000000000003a07b
[root@quaco ~]#


So the above is with a stress-ng-debuginfo package that doesn't matches
the binary installed, so build-id checkign fails, resolving symbols
fail, then:

[root@quaco ~]# rpm -q stress-ng-debuginfo
stress-ng-debuginfo-0.11.21-1.fc32.x86_64
[root@quaco ~]# rpm -q stress-ng
stress-ng-0.11.21-1.fc32.x86_64
[root@quaco ~]#

[root@quaco ~]# rpm -q stress-ng-debuginfo
stress-ng-debuginfo-0.11.21-1.fc32.x86_64
[root@quaco ~]# rpm -q stress-ng
stress-ng-0.11.21-1.fc32.x86_64
[root@quaco ~]# perf report | head -20
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 4K of event 'cycles'
# Event count (approx.): 3997318603
#
# Overhead Command Shared Object Symbol
# ........ ............. ............. .........................................
#
21.48% stress-ng-cpu stress-ng [.] is_prime
16.02% stress-ng-cpu stress-ng [.] stress_cpu_sieve
12.61% stress-ng-cpu stress-ng [.] stress_cpu_cpuid.sse2.2
11.94% stress-ng-cpu stress-ng [.] ackermann
8.24% stress-ng-cpu stress-ng [.] stress_cpu_correlate
3.82% stress-ng-cpu stress-ng [.] queens_try
2.63% stress-ng-cpu stress-ng [.] stress_cpu_nsqrt.sse2.2
2.46% stress-ng-cpu stress-ng [.] ccitt_crc16
2.25% stress-ng-cpu stress-ng [.] stress_cpu_complex_long_double.sse2.2
[root@quaco ~]#

[root@quaco ~]# perf report -v | head -20
build id event received for vmlinux: f72ec65d81949c5ba63ccaa16b59c79d1696bc4d [20]
build id event received for /usr/bin/stress-ng: 82b81bd823dcac393292faaaf40997723ce358a8 [20]
build id event received for [vdso]: a1f89b9b9d2093ae926c550a7de060d435277fbf [20]
build id event received for /usr/lib64/libm-2.31.so: fdf1f1d0761b7392e419d5d72e43d3fd3db6e184 [20]
build id event received for /usr/lib64/libc-2.31.so: d278249792061c6b74d1693ca59513be1def13f2 [20]
Looking at the vmlinux_path (8 entries long)
symsrc__init: build id mismatch for vmlinux.
Using /usr/lib/debug/lib/modules/5.8.14-200.fc32.x86_64/vmlinux for symbols
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 4K of event 'cycles'
# Event count (approx.): 3997318603
#
# Overhead Command Shared Object Symbol
# ........ ............. .................. ....................................................
#
21.48% stress-ng-cpu /usr/bin/stress-ng 0x35e80 l [.] is_prime
16.02% stress-ng-cpu /usr/bin/stress-ng 0x3bbf6 l [.] stress_cpu_sieve
12.61% stress-ng-cpu /usr/bin/stress-ng 0x65ec6 l [.] stress_cpu_cpuid.sse2.2
11.94% stress-ng-cpu /usr/bin/stress-ng 0x3c66b l [.] ackermann
8.24% stress-ng-cpu /usr/bin/stress-ng 0x39fd8 l [.] stress_cpu_correlate
3.82% stress-ng-cpu /usr/bin/stress-ng 0x64742 l [.] queens_try
2.63% stress-ng-cpu /usr/bin/stress-ng 0x7a0a8 l [.] stress_cpu_nsqrt.sse2.2
2.46% stress-ng-cpu /usr/bin/stress-ng 0x3400e l [.] ccitt_crc16
2.25% stress-ng-cpu /usr/bin/stress-ng 0x71761 l [.] stress_cpu_complex_long_double.sse2.2
[root@quaco ~]#
>
> jirka
>
> >
> > - Arnaldo
> >
> > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > > ---
> > > tools/perf/builtin-buildid-list.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/tools/perf/builtin-buildid-list.c b/tools/perf/builtin-buildid-list.c
> > > index e3ef75583514..87f5b1a4a7fa 100644
> > > --- a/tools/perf/builtin-buildid-list.c
> > > +++ b/tools/perf/builtin-buildid-list.c
> > > @@ -77,6 +77,9 @@ static int perf_session__list_build_ids(bool force, bool with_hits)
> > > perf_header__has_feat(&session->header, HEADER_AUXTRACE))
> > > with_hits = false;
> > >
> > > + if (!perf_header__has_feat(&session->header, HEADER_BUILD_ID))
> > > + with_hits = true;
> > > +
> > > /*
> > > * in pipe-mode, the only way to get the buildids is to parse
> > > * the record stream. Buildids are stored as RECORD_HEADER_BUILD_ID
> > > --
> > > 2.26.2
> > >
> >
> > --
> >
> > - Arnaldo
> >
>

--

- Arnaldo