168 lines
8.3 KiB
Plaintext
168 lines
8.3 KiB
Plaintext
Demonstrations of klockstat, the Linux eBPF/bcc version.
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klockstat traces kernel mutex lock events and display locks statistics
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# klockstat.py
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Tracing lock events... Hit Ctrl-C to end.
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^C
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Caller Avg Spin Count Max spin Total spin
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psi_avgs_work+0x2e 3675 5 5468 18379
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flush_to_ldisc+0x22 2833 2 4210 5667
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n_tty_write+0x30c 3914 1 3914 3914
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isig+0x5d 2390 1 2390 2390
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tty_buffer_flush+0x2a 1604 1 1604 1604
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commit_echoes+0x22 1400 1 1400 1400
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n_tty_receive_buf_common+0x3b9 1399 1 1399 1399
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Caller Avg Hold Count Max hold Total hold
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flush_to_ldisc+0x22 42558 2 76135 85116
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psi_avgs_work+0x2e 14821 5 20446 74106
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n_tty_receive_buf_common+0x3b9 12300 1 12300 12300
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n_tty_write+0x30c 10712 1 10712 10712
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isig+0x5d 3362 1 3362 3362
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tty_buffer_flush+0x2a 3078 1 3078 3078
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commit_echoes+0x22 3017 1 3017 3017
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Every caller to using kernel's mutex is displayed on every line.
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First portion of lines show the lock acquiring data, showing the
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amount of time it took to acquired given lock.
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'Caller' - symbol acquiring the mutex
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'Average Spin' - average time to acquire the mutex
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'Count' - number of times mutex was acquired
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'Max spin' - maximum time to acquire the mutex
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'Total spin' - total time spent in acquiring the mutex
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Second portion of lines show the lock holding data, showing the
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amount of time it took to hold given lock.
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'Caller' - symbol holding the mutex
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'Average Hold' - average time mutex was held
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'Count' - number of times mutex was held
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'Max hold' - maximum time mutex was held
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'Total hold' - total time spent in holding the mutex
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This works by tracing mutex_lock/unlock kprobes, updating the
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lock stats in maps and processing them in the python part.
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An -i option can be used to display stats in interval (5 seconds in example below):
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# klockstat.py -i 5
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Tracing lock events... Hit Ctrl-C to end.
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Caller Avg Spin Count Max spin Total spin
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psi_avgs_work+0x2e 3822 15 5650 57338
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flush_to_ldisc+0x22 4630 1 4630 4630
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work_fn+0x4f 4185 1 4185 4185
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Caller Avg Hold Count Max hold Total hold
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psi_avgs_work+0x2e 12155 15 15739 182329
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flush_to_ldisc+0x22 13809 1 13809 13809
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work_fn+0x4f 5274 1 5274 5274
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Caller Avg Spin Count Max spin Total spin
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psi_avgs_work+0x2e 3715 17 4374 63163
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Caller Avg Hold Count Max hold Total hold
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psi_avgs_work+0x2e 13141 17 19510 223399
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^C
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A -p option can be used to trace only selected process:
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# klockstat.py -p 883
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Tracing lock events... Hit Ctrl-C to end.
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^C
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Caller Avg Spin Count Max spin Total spin
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pipe_wait+0xa9 625 412686 16930 258277958
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pipe_read+0x3f 420 413425 16872 174017649
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pipe_write+0x35 471 413425 16765 194792253
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Caller Avg Hold Count Max hold Total hold
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pipe_read+0x3f 473 413425 20063 195773647
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pipe_wait+0xa9 604 412686 16972 249598153
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pipe_write+0x35 481 413425 16944 199008064
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A -c option can be used to display only callers with specific substring:
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# klockstat.py -c pipe_
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Tracing lock events... Hit Ctrl-C to end.
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^C
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Caller Avg Spin Count Max spin Total spin
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pipe_read+0x3f 422 469554 18665 198354705
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pipe_wait+0xa9 679 469536 17196 319017069
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pipe_write+0x35 469 469554 17057 220338525
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Caller Avg Hold Count Max hold Total hold
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pipe_write+0x35 638 469554 17330 299857180
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pipe_wait+0xa9 779 469535 16912 366047392
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pipe_read+0x3f 575 469554 13251 270005394
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An -n option can be used to display only specific number of callers:
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# klockstat.py -n 3
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Tracing lock events... Hit Ctrl-C to end.
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^C
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Caller Avg Spin Count Max spin Total spin
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pipe_read+0x3f 420 334120 16964 140632284
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pipe_wait+0xa9 688 334116 16876 229957062
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pipe_write+0x35 463 334120 16791 154981747
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Caller Avg Hold Count Max hold Total hold
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flush_to_ldisc+0x22 27754 3 63270 83264
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pipe_read+0x3f 571 334120 17123 190976463
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pipe_wait+0xa9 759 334115 17068 253747213
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An -s option can be used to display number of callers backtrace entries:
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# klockstat.py -n 1 -s 3
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Tracing lock events... Hit Ctrl-C to end.
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^C
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Caller Avg Spin Count Max spin Total spin
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pipe_wait+0xa9 685 811947 17376 556542328
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pipe_wait+0xa9
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pipe_read+0x206
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Caller Avg Hold Count Max hold Total hold
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flush_to_ldisc+0x22 28145 3 63872 84437
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flush_to_ldisc+0x22
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process_one_work+0x1b0
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Output can be sorted by using -S <fields> option on various
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fields, the acq_total will force the acquired table to be
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sorted on 'Total spin' column:
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# klockstat.py -S acq_total
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Tracing lock events... Hit Ctrl-C to end.
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^C
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Caller Avg Spin Count Max spin Total spin
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pipe_wait+0xa9 691 269343 17190 186263983
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pipe_write+0x35 464 269351 11730 125205417
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pipe_read+0x3f 422 269351 17107 113724697
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psi_avgs_work+0x2e 2499 11 4454 27494
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flush_to_ldisc+0x22 3111 3 5096 9334
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n_tty_write+0x30c 2764 1 2764 2764
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isig+0x5d 1287 1 1287 1287
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tty_buffer_flush+0x2a 961 1 961 961
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commit_echoes+0x22 892 1 892 892
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n_tty_receive_buf_common+0x3b9 868 1 868 868
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Caller Avg Hold Count Max hold Total hold
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pipe_wait+0xa9 788 269343 17128 212496240
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pipe_write+0x35 637 269351 17209 171596811
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pipe_read+0x3f 585 269351 11834 157606323
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psi_avgs_work+0x2e 8726 11 19177 95996
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flush_to_ldisc+0x22 22158 3 43731 66474
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n_tty_write+0x30c 9770 1 9770 9770
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n_tty_receive_buf_common+0x3b9 6830 1 6830 6830
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isig+0x5d 3114 1 3114 3114
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tty_buffer_flush+0x2a 2032 1 2032 2032
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commit_echoes+0x22 1616 1 1616 1616
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