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    perf db-export: Fix thread__exec_comm() · f1f66289
    Adrian Hunter 提交于
    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: NAdrian Hunter <adrian.hunter@intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: stable@vger.kernel.org
    Fixes: 65de51f9 ("perf tools: Identify which comms are from exec")
    Link: http://lkml.kernel.org/r/20190808064823.14846-1-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    f1f66289
thread.c 9.1 KB