linux-stable.git/tools/perf, branch v5.14.7

perf bench inject-buildid: Handle writen() errors

2021-09-22T10:39:30+00:00

[ Upstream commit edf7b4a2d85e37a1ee77156bddaed4aa6af9c5e1 ]

The build on fedora:35 and fedora:rawhide with clang is failing with:

  49    41.00 fedora:35                     : FAIL clang version 13.0.0 (Fedora 13.0.0~rc1-1.fc35)
    bench/inject-buildid.c:351:6: error: variable 'len' set but not used [-Werror,-Wunused-but-set-variable]
            u64 len = 0;
                ^
    1 error generated.
    make[3]: *** [/git/perf-5.14.0-rc7/tools/build/Makefile.build:139: bench] Error 2
  50    41.11 fedora:rawhide                : FAIL clang version 13.0.0 (Fedora 13.0.0~rc1-1.fc35)
    bench/inject-buildid.c:351:6: error: variable 'len' set but not used [-Werror,-Wunused-but-set-variable]
            u64 len = 0;
                ^
    1 error generated.
    make[3]: *** [/git/perf-5.14.0-rc7/tools/build/Makefile.build:139: bench] Error 2

That 'len' variable is not used at all, so just make sure all the
synthesize_RECORD() routines return ssize_t to propagate the writen()
return, as it may fail, ditch the 'ret' var and bail out if those
routines fail.

Fixes: 0bf02a0d80427f26 ("perf bench: Add build-id injection benchmark")
Acked-by: Namhyung Kim 
Link: http://lore.kernel.org/lkml/CAM9d7cgEZNSor+B+7Y2C+QYGme_v5aH0Zn0RLfxoQ+Fy83EHrg@mail.gmail.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf unwind: Do not overwrite FEATURE_CHECK_LDFLAGS-libunwind-{x86,aarch64}

2021-09-22T10:39:30+00:00

[ Upstream commit cdf32b44678c382a31dc183d9a767306915cda7b ]

When setting LIBUNWIND_DIR, we first set

 FEATURE_CHECK_LDFLAGS-libunwind-{aarch64,x86} = -L$(LIBUNWIND_DIR)/lib.


This happens a bit before, the overwritting, in:

  libunwind_arch_set_flags = $(eval $(libunwind_arch_set_flags_code))
  define libunwind_arch_set_flags_code
    FEATURE_CHECK_CFLAGS-libunwind-$(1)  = -I$(LIBUNWIND_DIR)/include
    FEATURE_CHECK_LDFLAGS-libunwind-$(1) = -L$(LIBUNWIND_DIR)/lib
  endef

  ifdef LIBUNWIND_DIR
    LIBUNWIND_CFLAGS  = -I$(LIBUNWIND_DIR)/include
    LIBUNWIND_LDFLAGS = -L$(LIBUNWIND_DIR)/lib
    LIBUNWIND_ARCHS = x86 x86_64 arm aarch64 debug-frame-arm debug-frame-aarch64
    $(foreach libunwind_arch,$(LIBUNWIND_ARCHS),$(call libunwind_arch_set_flags,$(libunwind_arch)))
  endif

Look at that 'foreach' on all the LIBUNWIND_ARCHS.


After commit 5c4d7c82c0dc ("perf unwind: Do not put libunwind-{x86,aarch64}
in FEATURE_TESTS_BASIC"), FEATURE_CHECK_LDFLAGS-libunwind-{x86,aarch64} is
overwritten. As a result, the remote libunwind libraries cannot be searched
from $(LIBUNWIND_DIR)/lib directory during feature check tests. Fix it with
variable appending.

Before this patch:

  perf$ make VF=1 LIBUNWIND_DIR=/opt/libunwind_aarch64
   BUILD:   Doing 'make -j16' parallel build
  
  ...
  ...                    libopencsd: [ OFF ]
  ...                 libunwind-x86: [ OFF ]
  ...              libunwind-x86_64: [ OFF ]
  ...                 libunwind-arm: [ OFF ]
  ...             libunwind-aarch64: [ OFF ]
  ...         libunwind-debug-frame: [ OFF ]
  ...     libunwind-debug-frame-arm: [ OFF ]
  ... libunwind-debug-frame-aarch64: [ OFF ]
  ...                           cxx: [ OFF ]
  

  perf$ cat ../build/feature/test-libunwind-aarch64.make.output
  /usr/bin/ld: cannot find -lunwind-aarch64
  /usr/bin/ld: cannot find -lunwind-aarch64
  collect2: error: ld returned 1 exit status

After this patch:

  perf$ make VF=1 LIBUNWIND_DIR=/opt/libunwind_aarch64
   BUILD:   Doing 'make -j16' parallel build
  
  ...                    libopencsd: [ OFF ]
  ...                 libunwind-x86: [ OFF ]
  ...              libunwind-x86_64: [ OFF ]
  ...                 libunwind-arm: [ OFF ]
  ...             libunwind-aarch64: [ on  ]
  ...         libunwind-debug-frame: [ OFF ]
  ...     libunwind-debug-frame-arm: [ OFF ]
  ... libunwind-debug-frame-aarch64: [ OFF ]
  ...                           cxx: [ OFF ]
  

  perf$ cat ../build/feature/test-libunwind-aarch64.make.output

  perf$ ldd ./perf
        linux-vdso.so.1 (0x00007ffdf07da000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f30953dc000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f30951d4000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f3094e36000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f3094c32000)
        libelf.so.1 => /usr/lib/x86_64-linux-gnu/libelf.so.1 (0x00007f3094a18000)
        libdw.so.1 => /usr/lib/x86_64-linux-gnu/libdw.so.1 (0x00007f30947cc000)
        libunwind-x86_64.so.8 => /usr/lib/x86_64-linux-gnu/libunwind-x86_64.so.8 (0x00007f30945ad000)
        libunwind.so.8 => /usr/lib/x86_64-linux-gnu/libunwind.so.8 (0x00007f3094392000)
        liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f309416c000)
        libunwind-aarch64.so.8 => not found
        libslang.so.2 => /lib/x86_64-linux-gnu/libslang.so.2 (0x00007f3093c8a000)
        libpython2.7.so.1.0 => /usr/local/lib/libpython2.7.so.1.0 (0x00007f309386b000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f309364e000)
        libnuma.so.1 => /usr/lib/x86_64-linux-gnu/libnuma.so.1 (0x00007f3093443000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3093052000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f3096097000)
        libbz2.so.1.0 => /lib/x86_64-linux-gnu/libbz2.so.1.0 (0x00007f3092e42000)
        libutil.so.1 => /lib/x86_64-linux-gnu/libutil.so.1 (0x00007f3092c3f000)

Fixes: 5c4d7c82c0dceccf ("perf unwind: Do not put libunwind-{x86,aarch64} in FEATURE_TESTS_BASIC")
Signed-off-by: Li Huafei 
Cc: Alexander Shishkin 
Cc: He Kuang 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Zhang Jinhao 
Link: http://lore.kernel.org/lkml/20210823134340.60955-1-lihuafei1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf config: Fix caching and memory leak in perf_home_perfconfig()

2021-09-22T10:39:30+00:00

[ Upstream commit 261f491133aecb943ccfdc3b3794e2d775607a87 ]

Acaict, perf_home_perfconfig() is supposed to cache the result of
home_perfconfig, which returns the default location of perfconfig for
the user, given the HOME environment variable.

However, the current implementation calls home_perfconfig every time
perf_home_perfconfig() is called (so no caching is actually performed),
replacing the previous pointer, thus also causing a memory leak.

This patch adds a check of whether either config or failed is set and,
in that case, directly returns config without calling home_perfconfig at
each invocation.

Fixes: f5f03e19ce14fc31 ("perf config: Add perf_home_perfconfig function")
Signed-off-by: Riccardo Mancini 
Cc: Alexander Shishkin 
Cc: Ian Rogers 
Cc: Jin Yao 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Song Liu 
Link: http://lore.kernel.org/lkml/20210820130817.740536-1-rickyman7@gmail.com
[ Removed needless double check for the 'failed' variable ]
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf machine: Initialize srcline string member in add_location struct

2021-09-22T10:39:20+00:00

commit 57f0ff059e3daa4e70a811cb1d31a49968262d20 upstream.

It's later supposed to be either a correct address or NULL. Without the
initialization, it may contain an undefined value which results in the
following segmentation fault:

  # perf top --sort comm -g --ignore-callees=do_idle

terminates with:

  #0  0x00007ffff56b7685 in __strlen_avx2 () from /lib64/libc.so.6
  #1  0x00007ffff55e3802 in strdup () from /lib64/libc.so.6
  #2  0x00005555558cb139 in hist_entry__init (callchain_size=, sample_self=true, template=0x7fffde7fb110, he=0x7fffd801c250) at util/hist.c:489
  #3  hist_entry__new (template=template@entry=0x7fffde7fb110, sample_self=sample_self@entry=true) at util/hist.c:564
  #4  0x00005555558cb4ba in hists__findnew_entry (hists=hists@entry=0x5555561d9e38, entry=entry@entry=0x7fffde7fb110, al=al@entry=0x7fffde7fb420,
      sample_self=sample_self@entry=true) at util/hist.c:657
  #5  0x00005555558cba1b in __hists__add_entry (hists=hists@entry=0x5555561d9e38, al=0x7fffde7fb420, sym_parent=, bi=bi@entry=0x0, mi=mi@entry=0x0,
      sample=sample@entry=0x7fffde7fb4b0, sample_self=true, ops=0x0, block_info=0x0) at util/hist.c:288
  #6  0x00005555558cbb70 in hists__add_entry (sample_self=true, sample=0x7fffde7fb4b0, mi=0x0, bi=0x0, sym_parent=, al=, hists=0x5555561d9e38)
      at util/hist.c:1056
  #7  iter_add_single_cumulative_entry (iter=0x7fffde7fb460, al=) at util/hist.c:1056
  #8  0x00005555558cc8a4 in hist_entry_iter__add (iter=iter@entry=0x7fffde7fb460, al=al@entry=0x7fffde7fb420, max_stack_depth=, arg=arg@entry=0x7fffffff7db0)
      at util/hist.c:1231
  #9  0x00005555557cdc9a in perf_event__process_sample (machine=, sample=0x7fffde7fb4b0, evsel=, event=, tool=0x7fffffff7db0)
      at builtin-top.c:842
  #10 deliver_event (qe=, qevent=) at builtin-top.c:1202
  #11 0x00005555558a9318 in do_flush (show_progress=false, oe=0x7fffffff80e0) at util/ordered-events.c:244
  #12 __ordered_events__flush (oe=oe@entry=0x7fffffff80e0, how=how@entry=OE_FLUSH__TOP, timestamp=timestamp@entry=0) at util/ordered-events.c:323
  #13 0x00005555558a9789 in __ordered_events__flush (timestamp=, how=, oe=) at util/ordered-events.c:339
  #14 ordered_events__flush (how=OE_FLUSH__TOP, oe=0x7fffffff80e0) at util/ordered-events.c:341
  #15 ordered_events__flush (oe=oe@entry=0x7fffffff80e0, how=how@entry=OE_FLUSH__TOP) at util/ordered-events.c:339
  #16 0x00005555557cd631 in process_thread (arg=0x7fffffff7db0) at builtin-top.c:1114
  #17 0x00007ffff7bb817a in start_thread () from /lib64/libpthread.so.0
  #18 0x00007ffff5656dc3 in clone () from /lib64/libc.so.6

If you look at the frame #2, the code is:

488	 if (he->srcline) {
489          he->srcline = strdup(he->srcline);
490          if (he->srcline == NULL)
491              goto err_rawdata;
492	 }

If he->srcline is not NULL (it is not NULL if it is uninitialized rubbish),
it gets strdupped and strdupping a rubbish random string causes the problem.

Also, if you look at the commit 1fb7d06a509e, it adds the srcline property
into the struct, but not initializing it everywhere needed.

Committer notes:

Now I see, when using --ignore-callees=do_idle we end up here at line
2189 in add_callchain_ip():

2181         if (al.sym != NULL) {
2182                 if (perf_hpp_list.parent && !*parent &&
2183                     symbol__match_regex(al.sym, &parent_regex))
2184                         *parent = al.sym;
2185                 else if (have_ignore_callees && root_al &&
2186                   symbol__match_regex(al.sym, &ignore_callees_regex)) {
2187                         /* Treat this symbol as the root,
2188                            forgetting its callees. */
2189                         *root_al = al;
2190                         callchain_cursor_reset(cursor);
2191                 }
2192         }

And the al that doesn't have the ->srcline field initialized will be
copied to the root_al, so then, back to:

1211 int hist_entry_iter__add(struct hist_entry_iter *iter, struct addr_location *al,
1212                          int max_stack_depth, void *arg)
1213 {
1214         int err, err2;
1215         struct map *alm = NULL;
1216
1217         if (al)
1218                 alm = map__get(al->map);
1219
1220         err = sample__resolve_callchain(iter->sample, &callchain_cursor, &iter->parent,
1221                                         iter->evsel, al, max_stack_depth);
1222         if (err) {
1223                 map__put(alm);
1224                 return err;
1225         }
1226
1227         err = iter->ops->prepare_entry(iter, al);
1228         if (err)
1229                 goto out;
1230
1231         err = iter->ops->add_single_entry(iter, al);
1232         if (err)
1233                 goto out;
1234

That al at line 1221 is what hist_entry_iter__add() (called from
sample__resolve_callchain()) saw as 'root_al', and then:

        iter->ops->add_single_entry(iter, al);

will go on with al->srcline with a bogus value, I'll add the above
sequence to the cset and apply, thanks!

Signed-off-by: Michael Petlan 
CC: Milian Wolff 
Cc: Jiri Olsa 
Fixes: 1fb7d06a509e ("perf report Use srcline from callchain for hist entries")
Link: https //lore.kernel.org/r/20210719145332.29747-1-mpetlan@redhat.com
Reported-by: Juri Lelli 
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Greg Kroah-Hartman

tools: Free BTF objects at various locations

2021-09-15T08:02:16+00:00

[ Upstream commit 369e955b3d1c12f6ec2e51a95911bb80ada55d79 ]

Make sure to call btf__free() (and not simply free(), which does not
free all pointers stored in the struct) on pointers to struct btf
objects retrieved at various locations.

These were found while updating the calls to btf__get_from_id().

Fixes: 999d82cbc044 ("tools/bpf: enhance test_btf file testing to test func info")
Fixes: 254471e57a86 ("tools/bpf: bpftool: add support for func types")
Fixes: 7b612e291a5a ("perf tools: Synthesize PERF_RECORD_* for loaded BPF programs")
Fixes: d56354dc4909 ("perf tools: Save bpf_prog_info and BTF of new BPF programs")
Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command")
Fixes: fa853c4b839e ("perf stat: Enable counting events for BPF programs")
Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20210729162028.29512-5-quentin@isovalent.com
Signed-off-by: Sasha Levin

Revert "perf map: Fix dso->nsinfo refcounting"

2021-07-30T21:26:22+00:00

This makes 'perf top' abort in some cases, and the right fix will
involve surgery that is too much to do at this stage, so revert for now
and fix it in the next merge window.

This reverts commit 2d6b74baa7147251c30a46c4996e8cc224aa2dc5.

Cc: Riccardo Mancini 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Krister Johansen 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Signed-off-by: Arnaldo Carvalho de Melo

perf pmu: Fix alias matching

2021-07-27T16:21:46+00:00

Commit c47a5599eda324ba ("perf tools: Fix pattern matching for same
substring in different PMU type"), may have fixed some alias matching,
but has broken some others.

Firstly it cannot handle the simple scenario of PMU name in form
pmu_name{digits} - it can only handle pmu_name_{digits}.

Secondly it cannot handle more complex matching in the case where we
have multiple tokens. In this scenario, the code failed to realise that
we may examine multiple substrings in the PMU name.

Fix in two ways:

- Change perf_pmu__valid_suffix() to accept a PMU name without '_' in the
  suffix

- Only pay attention to perf_pmu__valid_suffix() for the final token

Also add const qualifiers as necessary to avoid casting.

Fixes: c47a5599eda324ba ("perf tools: Fix pattern matching for same substring in different PMU type")
Signed-off-by: John Garry 
Tested-by: Jin Yao 
Cc: Alexander Shishkin 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lore.kernel.org/lkml/1626793819-79090-1-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo

perf cs-etm: Split --dump-raw-trace by AUX records

2021-07-27T15:50:56+00:00

Currently --dump-raw-trace skips queueing and splitting buffers because
of an early exit condition in cs_etm__process_auxtrace_info(). Once
that is removed we can print the split data by using the queues
and searching for split buffers with the same reference as the
one that is currently being processed.

This keeps the same behaviour of dumping in file order when an AUXTRACE
event appears, rather than moving trace dump to where AUX records are in
the file.

There will be a newline and size printout for each fragment. For example
this buffer is comprised of two AUX records, but was printed as one:

  0 0 0x8098 [0x30]: PERF_RECORD_AUXTRACE size: 0xa0  offset: 0  ref: 0x491a4dfc52fc0e6e  idx: 0  t

  . ... CoreSight ETM Trace data: size 160 bytes
          Idx:0; ID:10;   I_ASYNC : Alignment Synchronisation.
          Idx:12; ID:10;  I_TRACE_INFO : Trace Info.; INFO=0x0 { CC.0 }
          Idx:17; ID:10;  I_ADDR_L_64IS0 : Address, Long, 64 bit, IS0.; Addr=0x0000000000000000;
          Idx:80; ID:10;  I_ASYNC : Alignment Synchronisation.
          Idx:92; ID:10;  I_TRACE_INFO : Trace Info.; INFO=0x0 { CC.0 }
          Idx:97; ID:10;  I_ADDR_L_64IS0 : Address, Long, 64 bit, IS0.; Addr=0xFFFFDE2AD3FD76D4;

But is now printed as two fragments:

  0 0 0x8098 [0x30]: PERF_RECORD_AUXTRACE size: 0xa0  offset: 0  ref: 0x491a4dfc52fc0e6e  idx: 0  t

  . ... CoreSight ETM Trace data: size 80 bytes
          Idx:0; ID:10;   I_ASYNC : Alignment Synchronisation.
          Idx:12; ID:10;  I_TRACE_INFO : Trace Info.; INFO=0x0 { CC.0 }
          Idx:17; ID:10;  I_ADDR_L_64IS0 : Address, Long, 64 bit, IS0.; Addr=0x0000000000000000;

  . ... CoreSight ETM Trace data: size 80 bytes
          Idx:80; ID:10;  I_ASYNC : Alignment Synchronisation.
          Idx:92; ID:10;  I_TRACE_INFO : Trace Info.; INFO=0x0 { CC.0 }
          Idx:97; ID:10;  I_ADDR_L_64IS0 : Address, Long, 64 bit, IS0.; Addr=0xFFFFDE2AD3FD76D4;

Decoding errors that appeared in problematic files are now not present,
for example:

        Idx:808; ID:1c; I_BAD_SEQUENCE : Invalid Sequence in packet.[I_ASYNC]
        ...
        PKTP_ETMV4I_0016 : 0x0014 (OCSD_ERR_INVALID_PCKT_HDR) [Invalid packet header]; TrcIdx=822

Signed-off-by: James Clark 
Reviewed-by: Mathieu Poirier 
Tested-by: Leo Yan 
Cc: Al Grant 
Cc: Alexander Shishkin 
Cc: Anshuman Khandual 
Cc: Branislav Rankov 
Cc: Denis Nikitin 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Mark Rutland 
Cc: Mike Leach 
Cc: Namhyung Kim 
Cc: Suzuki Poulouse 
Cc: Will Deacon 
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20210624164303.28632-3-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf sched: Fix record failure when CONFIG_SCHEDSTATS is not set

2021-07-18T12:36:37+00:00

The tracepoints trace_sched_stat_{wait, sleep, iowait} are not exposed to user
if CONFIG_SCHEDSTATS is not set, "perf sched record" records the three events.
As a result, the command fails.

Before:

  #perf sched record sleep 1
  event syntax error: 'sched:sched_stat_wait'
                       \___ unknown tracepoint

  Error:  File /sys/kernel/tracing/events/sched/sched_stat_wait not found.
  Hint:   Perhaps this kernel misses some CONFIG_ setting to enable this feature?.

  Run 'perf list' for a list of valid events

   Usage: perf record [] []
      or: perf record [] --  []

      -e, --event    event selector. use 'perf list' to list available events

Solution:
  Check whether schedstat tracepoints are exposed. If no, these events are not recorded.

After:
  # perf sched record sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.163 MB perf.data (1091 samples) ]
  # perf sched report
  run measurement overhead: 4736 nsecs
  sleep measurement overhead: 9059979 nsecs
  the run test took 999854 nsecs
  the sleep test took 8945271 nsecs
  nr_run_events:        716
  nr_sleep_events:      785
  nr_wakeup_events:     0
  ...
  ------------------------------------------------------------

Fixes: 2a09b5de235a6 ("sched/fair: do not expose some tracepoints to user if CONFIG_SCHEDSTATS is not set")
Signed-off-by: Yang Jihong 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Steven Rostedt (VMware) 
Cc: Yafang Shao 
Link: http://lore.kernel.org/lkml/20210713112358.194693-1-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Fix add event failure when running 32-bit perf in a 64-bit kernel

2021-07-18T12:31:15+00:00

The "address" member of "struct probe_trace_point" uses long data type.
If kernel is 64-bit and perf program is 32-bit, size of "address"
variable is 32 bits.

As a result, upper 32 bits of address read from kernel are truncated, an
error occurs during address comparison in kprobe_warn_out_range().

Before:

  # perf probe -a schedule
  schedule is out of .text, skip it.
    Error: Failed to add events.

Solution:
  Change data type of "address" variable to u64 and change corresponding
address printing and value assignment.

After:

  # perf.new.new probe -a schedule
  Added new event:
    probe:schedule       (on schedule)

  You can now use it in all perf tools, such as:

          perf record -e probe:schedule -aR sleep 1

  # perf probe -l
    probe:schedule       (on schedule@kernel/sched/core.c)
  # perf record -e probe:schedule -aR sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.156 MB perf.data (1366 samples) ]
  # perf report --stdio
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 1K of event 'probe:schedule'
  # Event count (approx.): 1366
  #
  # Overhead  Command          Shared Object      Symbol
  # ........  ...............  .................  ............
  #
       6.22%  migration/0      [kernel.kallsyms]  [k] schedule
       6.22%  migration/1      [kernel.kallsyms]  [k] schedule
       6.22%  migration/2      [kernel.kallsyms]  [k] schedule
       6.22%  migration/3      [kernel.kallsyms]  [k] schedule
       6.15%  migration/10     [kernel.kallsyms]  [k] schedule
       6.15%  migration/11     [kernel.kallsyms]  [k] schedule
       6.15%  migration/12     [kernel.kallsyms]  [k] schedule
       6.15%  migration/13     [kernel.kallsyms]  [k] schedule
       6.15%  migration/14     [kernel.kallsyms]  [k] schedule
       6.15%  migration/15     [kernel.kallsyms]  [k] schedule
       6.15%  migration/4      [kernel.kallsyms]  [k] schedule
       6.15%  migration/5      [kernel.kallsyms]  [k] schedule
       6.15%  migration/6      [kernel.kallsyms]  [k] schedule
       6.15%  migration/7      [kernel.kallsyms]  [k] schedule
       6.15%  migration/8      [kernel.kallsyms]  [k] schedule
       6.15%  migration/9      [kernel.kallsyms]  [k] schedule
       0.22%  rcu_sched        [kernel.kallsyms]  [k] schedule
  ...
  #
  # (Cannot load tips.txt file, please install perf!)
  #

Signed-off-by: Yang Jihong 
Acked-by: Masami Hiramatsu 
Cc: Alexander Shishkin 
Cc: Frank Ch. Eigler 
Cc: Ian Rogers 
Cc: Jianlin Lv 
Cc: Jin Yao 
Cc: Jiri Olsa 
Cc: Li Huafei 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Srikar Dronamraju 
Link: http://lore.kernel.org/lkml/20210715063723.11926-1-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo