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Diffstat (limited to 'Documentation/trace/kprobetrace.txt')
| -rw-r--r-- | Documentation/trace/kprobetrace.txt | 34 |
1 files changed, 16 insertions, 18 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index 15415243a9a3..47aabeebbdf6 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -1,26 +1,23 @@ - Kprobe-based Event Tracer - ========================= + Kprobe-based Event Tracing + ========================== Documentation is written by Masami Hiramatsu Overview -------- -This tracer is similar to the events tracer which is based on Tracepoint -infrastructure. Instead of Tracepoint, this tracer is based on kprobes(kprobe -and kretprobe). It probes anywhere where kprobes can probe(this means, all -functions body except for __kprobes functions). +These events are similar to tracepoint based events. Instead of Tracepoint, +this is based on kprobes (kprobe and kretprobe). So it can probe wherever +kprobes can probe (this means, all functions body except for __kprobes +functions). Unlike the Tracepoint based event, this can be added and removed +dynamically, on the fly. -Unlike the function tracer, this tracer can probe instructions inside of -kernel functions. It allows you to check which instruction has been executed. +To enable this feature, build your kernel with CONFIG_KPROBE_TRACING=y. -Unlike the Tracepoint based events tracer, this tracer can add and remove -probe points on the fly. - -Similar to the events tracer, this tracer doesn't need to be activated via -current_tracer, instead of that, just set probe points via -/sys/kernel/debug/tracing/kprobe_events. And you can set filters on each -probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter. +Similar to the events tracer, this doesn't need to be activated via +current_tracer. Instead of that, add probe points via +/sys/kernel/debug/tracing/kprobe_events, and enable it via +/sys/kernel/debug/tracing/events/kprobes/<EVENT>/enabled. Synopsis of kprobe_events @@ -55,9 +52,9 @@ Per-Probe Event Filtering ------------------------- Per-probe event filtering feature allows you to set different filter on each probe and gives you what arguments will be shown in trace buffer. If an event -name is specified right after 'p:' or 'r:' in kprobe_events, the tracer adds -an event under tracing/events/kprobes/<EVENT>, at the directory you can see -'id', 'enabled', 'format' and 'filter'. +name is specified right after 'p:' or 'r:' in kprobe_events, it adds an event +under tracing/events/kprobes/<EVENT>, at the directory you can see 'id', +'enabled', 'format' and 'filter'. enabled: You can enable/disable the probe by writing 1 or 0 on it. @@ -71,6 +68,7 @@ filter: id: This shows the id of this probe event. + Event Profiling --------------- You can check the total number of probe hits and probe miss-hits via |