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

Message ID 20230705181256.3539027-6-vschneid@redhat.com
State New
Headers
Series context_tracking,x86: Defer some IPIs until a user->kernel transition |

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 <vschneid@redhat.com>
---
 Documentation/trace/events.rst | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
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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
 -------------------