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| author | Ross Zwisler <zwisler@chromium.org> | 2023-01-25 14:32:51 -0700 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2023-01-31 14:02:30 -0700 |
| commit | 2abfcd293b79baf62895894fa3ea2386ffbe6338 (patch) | |
| tree | b74867f24b7c6d6b6909856063d6c184a29195e0 /Documentation/trace/kprobetrace.rst | |
| parent | b05ada5615f844c3fdcf5e2a0fa35a4bc1a394f2 (diff) | |
| download | linux-stable-2abfcd293b79baf62895894fa3ea2386ffbe6338.tar.gz linux-stable-2abfcd293b79baf62895894fa3ea2386ffbe6338.tar.bz2 linux-stable-2abfcd293b79baf62895894fa3ea2386ffbe6338.zip | |
docs: ftrace: always use canonical ftrace path
The canonical location for the tracefs filesystem is at /sys/kernel/tracing.
But, from Documentation/trace/ftrace.rst:
Before 4.1, all ftrace tracing control files were within the debugfs
file system, which is typically located at /sys/kernel/debug/tracing.
For backward compatibility, when mounting the debugfs file system,
the tracefs file system will be automatically mounted at:
/sys/kernel/debug/tracing
Many parts of Documentation still reference this older debugfs path, so
let's update them to avoid confusion.
Signed-off-by: Ross Zwisler <zwisler@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230125213251.2013791-1-zwisler@google.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/trace/kprobetrace.rst')
| -rw-r--r-- | Documentation/trace/kprobetrace.rst | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst index fda155237be7..0d103074d3d2 100644 --- a/Documentation/trace/kprobetrace.rst +++ b/Documentation/trace/kprobetrace.rst @@ -17,10 +17,10 @@ To enable this feature, build your kernel with CONFIG_KPROBE_EVENTS=y. Similar to the event 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>/enable. +/sys/kernel/tracing/kprobe_events, and enable it via +/sys/kernel/tracing/events/kprobes/<EVENT>/enable. -You can also use /sys/kernel/debug/tracing/dynamic_events instead of +You can also use /sys/kernel/tracing/dynamic_events instead of kprobe_events. That interface will provide unified access to other dynamic events too. @@ -153,7 +153,7 @@ trigger: Event Profiling --------------- You can check the total number of probe hits and probe miss-hits via -/sys/kernel/debug/tracing/kprobe_profile. +/sys/kernel/tracing/kprobe_profile. The first column is event name, the second is the number of probe hits, the third is the number of probe miss-hits. @@ -177,7 +177,7 @@ Usage examples To add a probe as a new event, write a new definition to kprobe_events as below:: - echo 'p:myprobe do_sys_open dfd=%ax filename=%dx flags=%cx mode=+4($stack)' > /sys/kernel/debug/tracing/kprobe_events + echo 'p:myprobe do_sys_open dfd=%ax filename=%dx flags=%cx mode=+4($stack)' > /sys/kernel/tracing/kprobe_events This sets a kprobe on the top of do_sys_open() function with recording 1st to 4th arguments as "myprobe" event. Note, which register/stack entry is @@ -187,15 +187,15 @@ under tools/perf/). As this example shows, users can choose more familiar names for each arguments. :: - echo 'r:myretprobe do_sys_open $retval' >> /sys/kernel/debug/tracing/kprobe_events + echo 'r:myretprobe do_sys_open $retval' >> /sys/kernel/tracing/kprobe_events This sets a kretprobe on the return point of do_sys_open() function with recording return value as "myretprobe" event. You can see the format of these events via -/sys/kernel/debug/tracing/events/kprobes/<EVENT>/format. +/sys/kernel/tracing/events/kprobes/<EVENT>/format. :: - cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format + cat /sys/kernel/tracing/events/kprobes/myprobe/format name: myprobe ID: 780 format: @@ -218,7 +218,7 @@ You can see the format of these events via You can see that the event has 4 arguments as in the expressions you specified. :: - echo > /sys/kernel/debug/tracing/kprobe_events + echo > /sys/kernel/tracing/kprobe_events This clears all probe points. @@ -233,8 +233,8 @@ Right after definition, each event is disabled by default. For tracing these events, you need to enable it. :: - echo 1 > /sys/kernel/debug/tracing/events/kprobes/myprobe/enable - echo 1 > /sys/kernel/debug/tracing/events/kprobes/myretprobe/enable + echo 1 > /sys/kernel/tracing/events/kprobes/myprobe/enable + echo 1 > /sys/kernel/tracing/events/kprobes/myretprobe/enable Use the following command to start tracing in an interval. :: @@ -243,10 +243,10 @@ Use the following command to start tracing in an interval. Open something... # echo 0 > tracing_on -And you can see the traced information via /sys/kernel/debug/tracing/trace. +And you can see the traced information via /sys/kernel/tracing/trace. :: - cat /sys/kernel/debug/tracing/trace + cat /sys/kernel/tracing/trace # tracer: nop # # TASK-PID CPU# TIMESTAMP FUNCTION |