Documentation/trace/histogram-design.rst

360 pid, and later a sched_switch event that switches to that pid event
368           events/sched/sched_switch/trigger
574 sched_switch histogram                                                      | |
577 The sched_switch histogram paired with the above sched_waking               | |
579 sched_switch histogram is that it references a variable on the              | |
597 The diagram below describes the situation for the sched_switch              | |
601           events/sched/sched_switch/trigger                                 | |
705 So, in order to handle an event for the sched_switch histogram,
710 sched_switch histogram.  For each one of those, the referenced
723 uses it in the sched_switch trigger.  The sched_switch trigger also
728   # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0' >> events/sched/sched_switch/trigger
780 Moving on to the sched_switch trigger hist_debug output, in addition
787 In this example, the sched_switch trigger has a reference to a
796   # cat events/sched/sched_switch/hist_debug
852   # echo '!hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0' >> events/sched/sched_switch/trigger
864 sched_switch event, if we have a matching sched_waking event, in this
866 next_pid field on this sched_switch event, we retrieve the
874 next_pid isn't, since it's just naming a field in the sched_switch
889 context of the sched_switch histogram using the onmatch() handler and
901 Finally, we create a hist trigger on the sched_switch event that
908 	  /sys/kernel/tracing/events/sched/sched_switch/trigger
910 The diagram for the sched_switch event is similar to previous examples
1111 sched_switch event fields, next_pid and next_comm, to generate a
1115   # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,next_comm)' >> /sys/kernel/tracing/events/sched/sched_switch/trigger
1161 The sched_switch hist_debug output shows the same key and value fields
1178 0 var.idx on the sched_switch hist trigger, as do all the remaining
1184   # cat events/sched/sched_switch/hist_debug
1308   # echo '!hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,next_comm)' >> /sys/kernel/tracing/events/sched/sched_switch/trigger
1366           /sys/kernel/tracing/events/sched/sched_switch/trigger
1372           /sys/kernel/tracing/events/sched/sched_switch/trigger
1387 In this case, however, we set up the sched_switch trigger to save some
1388 sched_switch field values whenever we hit a new maximum latency.  For
1392   # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmax($wakeup_lat).save(next_comm,prev_pid,prev_prio,prev_comm)' >> events/sched/sched_switch/trigger
1437 The output of the sched_switch trigger shows the same val and key
1458   # cat events/sched/sched_switch/hist_debug
1605   # echo '!hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmax($wakeup_lat).save(next_comm,prev_pid,prev_prio,prev_comm)' >> events/sched/sched_switch/trigger
1622 the sched_switch trigger references a hist trigger field on another
1638 Here we set up a hist trigger on sched_switch to send a wakeup_latency
1642 it.  There isn't however any prio field on the sched_switch event so
1653 Here's the sched_switch trigger::
1655   # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,prio)' >> events/sched/sched_switch/trigger
1749 Looking at the sched_switch histogram below, we can see a reference to
1756   # cat events/sched/sched_switch/hist_debug
1866   # echo '!hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,prio)' >> events/sched/sched_switch/trigger
1887 For the sched_switch trigger, instead of using $waking_pid directly in
1892   # echo 'hist:keys=next_pid:woken_pid=$waking_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,$woken_pid,next_comm)' >> events/sched/sched_switch/trigger
1948 The sched_switch hist_debug output shows that a variable named
1979   # cat events/sched/sched_switch/hist_debug
2111   # echo '!hist:keys=next_pid:woken_pid=$waking_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,$woken_pid,next_comm)' >> events/sched/sched_switch/trigger