linux-kernel - [for-next][PATCH 09/14] tracing/filters: Document cpumask filtering

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Message-ID: <20230824021852.187790824@goodmis.org>
Date:   Wed, 23 Aug 2023 22:18:21 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.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>,
        Valentin Schneider <vschneid@...hat.com>
Subject: [for-next][PATCH 09/14] tracing/filters: Document cpumask filtering

From: Valentin Schneider <vschneid@...hat.com>

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

Link: https://lkml.kernel.org/r/20230707172155.70873-10-vschneid@redhat.com

Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Jonathan Corbet <corbet@....net>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Leonardo Bras <leobras@...hat.com>
Cc: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Valentin Schneider <vschneid@...hat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 Documentation/trace/events.rst | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index f5fcb8e1218f..34108d5a55b4 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::
+
+  CPUS{$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 & CPUS{17-42}
+
 5.2 Setting filters
 -------------------
 
-- 
2.40.1