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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/histogram-design.rst | |
| parent | b05ada5615f844c3fdcf5e2a0fa35a4bc1a394f2 (diff) | |
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/histogram-design.rst')
| -rw-r--r-- | Documentation/trace/histogram-design.rst | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/trace/histogram-design.rst b/Documentation/trace/histogram-design.rst index 088c8cce738b..5765eb3e9efa 100644 --- a/Documentation/trace/histogram-design.rst +++ b/Documentation/trace/histogram-design.rst @@ -14,7 +14,7 @@ tracing_map.c. Note: All the ftrace histogram command examples assume the working directory is the ftrace /tracing directory. For example:: - # cd /sys/kernel/debug/tracing + # cd /sys/kernel/tracing Also, the histogram output displayed for those commands will be generally be truncated - only enough to make the point is displayed. @@ -905,7 +905,7 @@ means it will be automatically converted into a field variable:: # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \ onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid)' >> - /sys/kernel/debug/tracing/events/sched/sched_switch/trigger + /sys/kernel/tracing/events/sched/sched_switch/trigger The diagram for the sched_switch event is similar to previous examples but shows the additional field_vars[] array for hist_data and shows @@ -1112,7 +1112,7 @@ sched_switch event fields, next_pid and next_comm, to generate a wakeup_latency trace event. The next_pid and next_comm event fields are automatically converted into field variables for this purpose:: - # 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/debug/tracing/events/sched/sched_switch/trigger + # 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 The sched_waking hist_debug output shows the same data as in the previous test example:: @@ -1305,7 +1305,7 @@ and event name for the onmatch() handler:: The commands below can be used to clean things up for the next test:: - # 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/debug/tracing/events/sched/sched_switch/trigger + # 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 # echo '!hist:keys=pid:ts0=common_timestamp.usecs' >> events/sched/sched_waking/trigger @@ -1363,13 +1363,13 @@ with the save() and snapshot() actions. For example:: # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \ onmax($wakeup_lat).save(next_comm,prev_pid,prev_prio,prev_comm)' >> - /sys/kernel/debug/tracing/events/sched/sched_switch/trigger + /sys/kernel/tracing/events/sched/sched_switch/trigger or:: # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \ onmax($wakeup_lat).snapshot()' >> - /sys/kernel/debug/tracing/events/sched/sched_switch/trigger + /sys/kernel/tracing/events/sched/sched_switch/trigger save() action field variable test --------------------------------- |