ftrace: take advantage of variable length entries
Now that the underlining ring buffer for ftrace now hold variable length
entries, we can take advantage of this by only storing the size of the
actual event into the buffer. This happens to increase the number of
entries in the buffer dramatically.
We can also get rid of the "trace_cont" operation, but I'm keeping that
until we have no more users. Some of the ftrace tracers can now change
their code to adapt to this new feature.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f6965f7..e541a6b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -27,9 +27,24 @@
};
/*
+ * The trace entry - the most basic unit of tracing. This is what
+ * is printed in the end as a single line in the trace output, such as:
+ *
+ * bash-15816 [01] 235.197585: idle_cpu <- irq_enter
+ */
+struct trace_entry {
+ unsigned char type;
+ unsigned char cpu;
+ unsigned char flags;
+ unsigned char preempt_count;
+ int pid;
+};
+
+/*
* Function trace entry - function address and parent function addres:
*/
struct ftrace_entry {
+ struct trace_entry ent;
unsigned long ip;
unsigned long parent_ip;
};
@@ -39,6 +54,7 @@
* Context switch trace entry - which task (and prio) we switched from/to:
*/
struct ctx_switch_entry {
+ struct trace_entry ent;
unsigned int prev_pid;
unsigned char prev_prio;
unsigned char prev_state;
@@ -52,6 +68,7 @@
* Special (free-form) trace entry:
*/
struct special_entry {
+ struct trace_entry ent;
unsigned long arg1;
unsigned long arg2;
unsigned long arg3;
@@ -64,6 +81,7 @@
#define FTRACE_STACK_ENTRIES 8
struct stack_entry {
+ struct trace_entry ent;
unsigned long caller[FTRACE_STACK_ENTRIES];
};
@@ -71,10 +89,34 @@
* ftrace_printk entry:
*/
struct print_entry {
+ struct trace_entry ent;
unsigned long ip;
char buf[];
};
+#define TRACE_OLD_SIZE 88
+
+struct trace_field_cont {
+ unsigned char type;
+ /* Temporary till we get rid of this completely */
+ char buf[TRACE_OLD_SIZE - 1];
+};
+
+struct trace_mmiotrace_rw {
+ struct trace_entry ent;
+ struct mmiotrace_rw rw;
+};
+
+struct trace_mmiotrace_map {
+ struct trace_entry ent;
+ struct mmiotrace_map map;
+};
+
+struct trace_boot {
+ struct trace_entry ent;
+ struct boot_trace initcall;
+};
+
/*
* trace_flag_type is an enumeration that holds different
* states when a trace occurs. These are:
@@ -92,46 +134,7 @@
TRACE_FLAG_CONT = 0x10,
};
-/*
- * The trace field - the most basic unit of tracing. This is what
- * is printed in the end as a single line in the trace output, such as:
- *
- * bash-15816 [01] 235.197585: idle_cpu <- irq_enter
- */
-struct trace_field {
- char cpu;
- char flags;
- char preempt_count;
- int pid;
- union {
- struct ftrace_entry fn;
- struct ctx_switch_entry ctx;
- struct special_entry special;
- struct stack_entry stack;
- struct print_entry print;
- struct mmiotrace_rw mmiorw;
- struct mmiotrace_map mmiomap;
- struct boot_trace initcall;
- };
-};
-
-struct trace_field_cont {
- char buf[sizeof(struct trace_field)];
-};
-
-struct trace_entry {
- char type;
- union {
- struct trace_field field;
- struct trace_field_cont cont;
- };
-};
-
-#define TRACE_ENTRY_SIZE sizeof(struct trace_entry)
#define TRACE_BUF_SIZE 1024
-#define TRACE_PRINT_BUF_SIZE \
- (sizeof(struct trace_field) - offsetof(struct trace_field, print.buf))
-#define TRACE_CONT_BUF_SIZE sizeof(struct trace_field)
/*
* The CPU trace array - it consists of thousands of trace entries