linux-kernel - [RFC PATCH 5/5] tracing/filters: Document cpumask filtering

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Message-Id: <20230609150324.143538-6-vschneid@redhat.com>
Date:   Fri,  9 Jun 2023 16:03:24 +0100
From:   Valentin Schneider <vschneid@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Leonardo Bras <leobras@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: [RFC PATCH 5/5] tracing/filters: Document cpumask filtering

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

Signed-off-by: Valentin Schneider <vschneid@...hat.com>
---
 Documentation/trace/events.rst | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

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
 -------------------
 
-- 
2.31.1