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Diffstat (limited to 'Documentation/trace')
| -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 @@ | |||
| 1 | Kprobe-based Event Tracer | 1 | Kprobe-based Event Tracing |
| 2 | ========================= | 2 | ========================== |
| 3 | 3 | ||
| 4 | Documentation is written by Masami Hiramatsu | 4 | Documentation is written by Masami Hiramatsu |
| 5 | 5 | ||
| 6 | 6 | ||
| 7 | Overview | 7 | Overview |
| 8 | -------- | 8 | -------- |
| 9 | This tracer is similar to the events tracer which is based on Tracepoint | 9 | These events are similar to tracepoint based events. Instead of Tracepoint, |
| 10 | infrastructure. Instead of Tracepoint, this tracer is based on kprobes(kprobe | 10 | this is based on kprobes (kprobe and kretprobe). So it can probe wherever |
| 11 | and kretprobe). It probes anywhere where kprobes can probe(this means, all | 11 | kprobes can probe (this means, all functions body except for __kprobes |
| 12 | functions body except for __kprobes functions). | 12 | functions). Unlike the Tracepoint based event, this can be added and removed |
| 13 | dynamically, on the fly. | ||
| 13 | 14 | ||
| 14 | Unlike the function tracer, this tracer can probe instructions inside of | 15 | To enable this feature, build your kernel with CONFIG_KPROBE_TRACING=y. |
| 15 | kernel functions. It allows you to check which instruction has been executed. | ||
| 16 | 16 | ||
| 17 | Unlike the Tracepoint based events tracer, this tracer can add and remove | 17 | Similar to the events tracer, this doesn't need to be activated via |
| 18 | probe points on the fly. | 18 | current_tracer. Instead of that, add probe points via |
| 19 | 19 | /sys/kernel/debug/tracing/kprobe_events, and enable it via | |
| 20 | Similar to the events tracer, this tracer doesn't need to be activated via | 20 | /sys/kernel/debug/tracing/events/kprobes/<EVENT>/enabled. |
| 21 | current_tracer, instead of that, just set probe points via | ||
| 22 | /sys/kernel/debug/tracing/kprobe_events. And you can set filters on each | ||
| 23 | probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter. | ||
| 24 | 21 | ||
| 25 | 22 | ||
| 26 | Synopsis of kprobe_events | 23 | Synopsis of kprobe_events |
| @@ -55,9 +52,9 @@ Per-Probe Event Filtering | |||
| 55 | ------------------------- | 52 | ------------------------- |
| 56 | Per-probe event filtering feature allows you to set different filter on each | 53 | Per-probe event filtering feature allows you to set different filter on each |
| 57 | probe and gives you what arguments will be shown in trace buffer. If an event | 54 | probe and gives you what arguments will be shown in trace buffer. If an event |
| 58 | name is specified right after 'p:' or 'r:' in kprobe_events, the tracer adds | 55 | name is specified right after 'p:' or 'r:' in kprobe_events, it adds an event |
| 59 | an event under tracing/events/kprobes/<EVENT>, at the directory you can see | 56 | under tracing/events/kprobes/<EVENT>, at the directory you can see 'id', |
| 60 | 'id', 'enabled', 'format' and 'filter'. | 57 | 'enabled', 'format' and 'filter'. |
| 61 | 58 | ||
| 62 | enabled: | 59 | enabled: |
| 63 | You can enable/disable the probe by writing 1 or 0 on it. | 60 | You can enable/disable the probe by writing 1 or 0 on it. |
| @@ -71,6 +68,7 @@ filter: | |||
| 71 | id: | 68 | id: |
| 72 | This shows the id of this probe event. | 69 | This shows the id of this probe event. |
| 73 | 70 | ||
| 71 | |||
| 74 | Event Profiling | 72 | Event Profiling |
| 75 | --------------- | 73 | --------------- |
| 76 | You can check the total number of probe hits and probe miss-hits via | 74 | You can check the total number of probe hits and probe miss-hits via |