linux-stable.git/tools/perf/util/thread.c, branch linux-4.9.y

perf db-export: Fix thread__exec_comm()

2019-08-25T08:51:20+00:00

commit 3de7ae0b2a1d86dbb23d0cb135150534fdb2e836 upstream.

Threads synthesized from /proc have comms with a start time of zero, and
not marked as "exec". Currently, there can be 2 such comms. The first is
created by processing a synthesized fork event and is set to the
parent's comm string, and the second by processing a synthesized comm
event set to the thread's current comm string.

In the absence of an "exec" comm, thread__exec_comm() picks the last
(oldest) comm, which, in the case above, is the parent's comm string.
For a main thread, that is very probably wrong. Use the second-to-last
in that case.

This affects only db-export because it is the only user of
thread__exec_comm().

Example:

  $ sudo perf record -a -o pt-a-sleep-1 -e intel_pt//u -- sleep 1
  $ sudo chown ahunter pt-a-sleep-1

Before:

  $ perf script -i pt-a-sleep-1 --itrace=bep -s tools/perf/scripts/python/export-to-sqlite.py pt-a-sleep-1.db branches calls
  $ sqlite3 -header -column pt-a-sleep-1.db 'select * from comm_threads_view'
  comm_id     command     thread_id   pid         tid
  ----------  ----------  ----------  ----------  ----------
  1           swapper     1           0           0
  2           rcu_sched   2           10          10
  3           kthreadd    3           78          78
  5           sudo        4           15180       15180
  5           sudo        5           15180       15182
  7           kworker/4:  6           10335       10335
  8           kthreadd    7           55          55
  10          systemd     8           865         865
  10          systemd     9           865         875
  13          perf        10          15181       15181
  15          sleep       10          15181       15181
  16          kworker/3:  11          14179       14179
  17          kthreadd    12          29376       29376
  19          systemd     13          746         746
  21          systemd     14          401         401
  23          systemd     15          879         879
  23          systemd     16          879         945
  25          kthreadd    17          556         556
  27          kworker/u1  18          14136       14136
  28          kworker/u1  19          15021       15021
  29          kthreadd    20          509         509
  31          systemd     21          836         836
  31          systemd     22          836         967
  33          systemd     23          1148        1148
  33          systemd     24          1148        1163
  35          kworker/2:  25          17988       17988
  36          kworker/0:  26          13478       13478

After:

  $ perf script -i pt-a-sleep-1 --itrace=bep -s tools/perf/scripts/python/export-to-sqlite.py pt-a-sleep-1b.db branches calls
  $ sqlite3 -header -column pt-a-sleep-1b.db 'select * from comm_threads_view'
  comm_id     command     thread_id   pid         tid
  ----------  ----------  ----------  ----------  ----------
  1           swapper     1           0           0
  2           rcu_sched   2           10          10
  3           kswapd0     3           78          78
  4           perf        4           15180       15180
  4           perf        5           15180       15182
  6           kworker/4:  6           10335       10335
  7           kcompactd0  7           55          55
  8           accounts-d  8           865         865
  8           accounts-d  9           865         875
  10          perf        10          15181       15181
  12          sleep       10          15181       15181
  13          kworker/3:  11          14179       14179
  14          kworker/1:  12          29376       29376
  15          haveged     13          746         746
  16          systemd-jo  14          401         401
  17          NetworkMan  15          879         879
  17          NetworkMan  16          879         945
  19          irq/131-iw  17          556         556
  20          kworker/u1  18          14136       14136
  21          kworker/u1  19          15021       15021
  22          kworker/u1  20          509         509
  23          thermald    21          836         836
  23          thermald    22          836         967
  25          unity-sett  23          1148        1148
  25          unity-sett  24          1148        1163
  27          kworker/2:  25          17988       17988
  28          kworker/0:  26          13478       13478

Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org
Fixes: 65de51f93ebf ("perf tools: Identify which comms are from exec")
Link: http://lkml.kernel.org/r/20190808064823.14846-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Greg Kroah-Hartman

perf tools: Experiment with cppcheck

2016-10-03T14:24:13+00:00

Experimenting a bit using cppcheck[1], a static checker brought to my
attention by Colin, reducing the scope of some variables, reducing the
line of source code lines in the process:

  $ cppcheck --enable=style tools/perf/util/thread.c
  Checking tools/perf/util/thread.c...
  [tools/perf/util/thread.c:17]: (style) The scope of the variable 'leader' can be reduced.
  [tools/perf/util/thread.c:133]: (style) The scope of the variable 'err' can be reduced.
  [tools/perf/util/thread.c:273]: (style) The scope of the variable 'err' can be reduced.

Will continue later, but these are already useful, keep them.

1: https://sourceforge.net/p/cppcheck/wiki/Home/

Cc: Adrian Hunter 
Cc: Colin Ian King 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-ixws7lbycihhpmq9cc949ti6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Call unwind__prepare_access for forked thread

2016-07-04T23:27:25+00:00

Currently we call unwind__prepare_access for map event.  In case we
report fork event the thread inherits its parent's maps and
unwind__prepare_access is never called for the thread.

This causes unwind__get_entries seeing uninitialized
unwind_libunwind_ops and thus returning no callchain.

Adding unwind__prepare_access calls for fork even processing.

Signed-off-by: Jiri Olsa 
Cc: David Ahern 
Cc: He Kuang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1467634583-29147-5-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Add initialized arg into unwind__prepare_access

2016-07-04T23:27:12+00:00

Adding initialized arg into unwind__prepare_access to get feedback about
the initialization state.

It's not possible to get it from error code, because we return 0 even in
case we don't recognize dso, which is valid.

The 'initialized' value is used in following patch to speedup
unwind__prepare_access calls logic in fork path.

Signed-off-by: Jiri Olsa 
Cc: David Ahern 
Cc: He Kuang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1467634583-29147-4-git-send-email-jolsa@kernel.org
[ Remove ; after static inline function signatures, fixes build break ]
Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Check the target platform before assigning unwind methods

2016-06-07T18:09:36+00:00

Currently, 'perf script' uses host unwind methods to parse perf.data
callchain info without taking the target architecture into account, i.e.
assuming the perf.data file was generated on the same machine where the
analysis is being performed. So we get wrong result without any warnings
when unwinding callchains of x86(32-bit) on x86(64-bit) machine.

This patch adds an extra step that checks the target platform before
assigning unwind methods. In later patches in this series, we can use
this info to assign the right unwind methods for supported platforms.

Committer note:

After fixing it to register the local unwinder for live mode tools
('perf trace', 'perf top'), i.e. tools that don't use a perf.data file,
it works as intended and passes the 'perf test unwind' test:

  # perf trace -e nanosleep --call dwarf usleep 1
     0.328 ( 0.058 ms): usleep/11115 nanosleep(rqtp: 0x7fff083fa480) = 0
                                       __nanosleep_nocancel+0x7 (/usr/lib64/libc-2.22.so)
                                       usleep+0x34 (/usr/lib64/libc-2.22.so)
                                       main+0x1eb (/usr/bin/usleep)
                                       __libc_start_main+0xf0 (/usr/lib64/libc-2.22.so)
                                       _start+0x29 (/usr/bin/usleep)
  # perf test 48
  48: Test dwarf unwind         : Ok
  #

Signed-off-by: He Kuang 
Acked-by: Jiri Olsa 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: David Ahern 
Cc: Ekaterina Tumanova 
Cc: Josh Poimboeuf 
Cc: Kan Liang 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Sukadev Bhattiprolu 
Cc: Wang Nan 
Link: http://lkml.kernel.org/r/1464924803-22214-11-git-send-email-hekuang@huawei.com
[ Fixed exit path for 'live' mode tools, where we need to default to local unwinding ]
Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Move unwind__prepare_access from thread_new into thread__insert_map

2016-06-07T15:08:52+00:00

To determine the libunwind methods to use, we should get the
32bit/64bit information from maps of a thread. When a thread is newly
created, the information is not prepared. This patch moves
unwind__prepare_access() into thread__insert_map() so we can get the
information we need from maps. Meanwhile, let thread__insert_map()
return value and show messages on error.

Signed-off-by: He Kuang 
Acked-by: Jiri Olsa 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: David Ahern 
Cc: Ekaterina Tumanova 
Cc: Josh Poimboeuf 
Cc: Kan Liang 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Sukadev Bhattiprolu 
Cc: Wang Nan 
Link: http://lkml.kernel.org/r/1464924803-22214-5-git-send-email-hekuang@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Adopt get_main_thread from db-export.c

2016-05-30T15:41:43+00:00

Move the get_main_thread function from db-export.c to thread.c so that
it can be used elsewhere.

Signed-off-by: Andi Kleen 
Cc: Jiri Olsa 
Link: http://lkml.kernel.org/r/1464051145-19968-2-git-send-email-andi@firstfloor.org
[ Removed leftover bits from db-export.h ]
Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Introduce method to set comm from /proc/pid/self

2016-04-26T16:15:00+00:00

Will be used for lazy comm loading in 'perf trace'.

Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Milian Wolff 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-7ogbkuoka1y2qsmcckqxvl5m@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Remove duplicate const qualifier

2016-04-25T21:12:25+00:00

Signed-off-by: Eric Engestrom 
Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1461577678-29517-1-git-send-email-eric.engestrom@imgtec.com
Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Fix reference count initial state

2015-12-14T15:08:55+00:00

We should always return from thread__new(), the constructor, with the
object with a reference count of one, so that:

     struct thread *thread = thread__new();
     thread__put(thread);

Will call thread__delete().

If any reference is made to that 'thread' variable, it better use
thread__get(thread) to hold a reference.

We were returning with thread->refcnt set to zero, fix it and some cases
where thread__delete() was being called, which were not a problem
because just one reference was being used, now that we set it to 1, use
thread__put() instead.

Reported-by: Masami Hiramatsu 
Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-4b9mkuk66to4ecckpmpvqx6s@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo