4 Commits
Author SHA1 Message Date
Beau Belgrave 9211ddaa78 tracing/user_events: Use write ABI in example
The ABI has changed to use a remote write approach. Update the example
to show the expected use of this new ABI. Also remove debugfs
path and use tracefs to ensure example works in more environments.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Beau Belgrave <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
2023-03-29 06:52:09 -04:00
Ross Zwisler 2455f0e124 tracing: 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 comments and Kconfig help messages in the tracing code still refer
to this older debugfs path, so let's update them to avoid confusion.

Link: https://lore.kernel.org/linux-trace-kernel/[email protected]

Acked-by: Masami Hiramatsu (Google) <[email protected]>
Reviewed-by: Mukesh Ojha <[email protected]>
Signed-off-by: Ross Zwisler <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
2023-02-18 14:34:09 -05:00
Beau Belgrave 39d6d08b2e tracing/user_events: Use bits vs bytes for enabled status page data
User processes may require many events and when they do the cache
performance of a byte index status check is less ideal than a bit index.
The previous event limit per-page was 4096, the new limit is 32,768.

This change adds a bitwise index to the user_reg struct. Programs check
that the bit at status_bit has a bit set within the status page(s).

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lore.kernel.org/all/[email protected]/

Suggested-by: Mathieu Desnoyers <[email protected]>
Signed-off-by: Beau Belgrave <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
2022-09-29 10:17:37 -04:00
Beau Belgrave c57eb47815 user_events: Add sample code for typical usage
Add sample code for user_events typical usage to show how to register
and monitor status, as well as to write out data.

Link: https://lkml.kernel.org/r/[email protected]

Acked-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Beau Belgrave <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
2022-02-10 22:38:15 -05:00