[RFC,05/14] tracing/filters: Document cpumask filtering

Commit Message

Valentin Schneider July 5, 2023, 6:12 p.m. UTC

Cpumask, scalar and CPU fields can now be filtered by a user-provided
cpumask, document the syntax.

Signed-off-by: Valentin Schneider <[e-mail]>
---
 Documentation/trace/events.rst | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Patch

diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index f5fcb8e1218f6..e9bc9f23891a0 100644
--- a/Documentation/trace/events.rst
+++ b/Documentation/trace/events.rst
@@ -219,6 +219,20 @@  the function "security_prepare_creds" and less than the end of that function.
 The ".function" postfix can only be attached to values of size long, and can only
 be compared with "==" or "!=".
 
+Cpumask fields or scalar fields that encode a CPU number can be filtered using
+a user-provided cpumask in cpulist format. The format is as follows::
+
+  MASK{$cpulist}
+
+Operators available to cpumask filtering are:
+
+& (intersection), ==, !=
+
+For example, this will filter events that have their .target_cpu field present
+in the given cpumask::
+
+  target_cpu & MASK{17-42}
+
 5.2 Setting filters
 -------------------