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Diffstat (limited to 'Documentation/trace/histogram.txt')
| -rw-r--r-- | Documentation/trace/histogram.txt | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt index be612ca79455..0aec2d8e166b 100644 --- a/Documentation/trace/histogram.txt +++ b/Documentation/trace/histogram.txt @@ -188,6 +188,26 @@ interpreted as microseconds. cpu int - the cpu on which the event occurred. + Extended error information + -------------------------- + + For some error conditions encountered when invoking a hist trigger + command, extended error information is available via the + corresponding event's 'hist' file. Reading the hist file after an + error will display more detailed information about what went wrong, + if information is available. This extended error information will + be available until the next hist trigger command for that event. + + If available for a given error condition, the extended error + information and usage takes the following form: + + # echo xxx > /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger + echo: write error: Invalid argument + + # cat /sys/kernel/debug/tracing/events/sched/sched_wakeup/hist + ERROR: Couldn't yyy: zzz + Last command: xxx + 6.2 'hist' trigger examples --------------------------- |