linux-kernel - [PATCH v4 3/6] tracing: Add "last_func_repeats" to struct trace

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Message-Id: <20210415181854.147448-4-y.karadz@gmail.com>
Date:   Thu, 15 Apr 2021 21:18:51 +0300
From:   "Yordan Karadzhov (VMware)" <y.karadz@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     rostedt@...dmis.org, tglx@...utronix.de, peterz@...radead.org,
        "Yordan Karadzhov (VMware)" <y.karadz@...il.com>
Subject: [PATCH v4 3/6] tracing: Add "last_func_repeats" to struct trace_array

The field is used to keep track of the consecutive (on the same CPU) calls
of a single function. This information is needed in order to consolidate
the function tracing record in the cases when a single function is called
number of times.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@...il.com>
---
 kernel/trace/trace.c |  1 +
 kernel/trace/trace.h | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 507a30bf26e4..82833be07c1e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9104,6 +9104,7 @@ static int __remove_instance(struct trace_array *tr)
 	ftrace_clear_pids(tr);
 	ftrace_destroy_function_files(tr);
 	tracefs_remove(tr->dir);
+	free_percpu(tr->last_func_repeats);
 	free_trace_buffers(tr);
 
 	for (i = 0; i < tr->nr_topts; i++) {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6a5b4c2a0fa7..a4f1b66049fd 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -262,6 +262,17 @@ struct cond_snapshot {
 	cond_update_fn_t		update;
 };
 
+/*
+ * struct trace_func_repeats - used to keep track of the consecutive
+ * (on the same CPU) calls of a single function.
+ */
+struct trace_func_repeats {
+	unsigned long	ip;
+	unsigned long	parent_ip;
+	unsigned long	count;
+	u64		ts_last_call;
+};
+
 /*
  * The trace array - an array of per-CPU trace arrays. This is the
  * highest level data structure that individual tracers deal with.
@@ -358,6 +369,7 @@ struct trace_array {
 #ifdef CONFIG_TRACER_SNAPSHOT
 	struct cond_snapshot	*cond_snapshot;
 #endif
+	struct trace_func_repeats	__percpu *last_func_repeats;
 };
 
 enum {
-- 
2.25.1