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Subject[PATCH 1/5] function_graph: Support displaying relative timestamp
Date
When function_graph is used for latency tracers, relative timestamp
is more straightforward than absolute timestamp as function trace
does. This change adds relative timestamp support to function_graph
and applies to latency tracers (wakeup and irqsoff).

Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
kernel/trace/trace.h | 9 +++++----
kernel/trace/trace_functions_graph.c | 25 +++++++++++++++++++++++++
kernel/trace/trace_irqsoff.c | 2 +-
kernel/trace/trace_sched_wakeup.c | 2 +-
4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 08900828d282..a34fa5e76abb 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -855,10 +855,11 @@ static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash)
#define TRACE_GRAPH_PRINT_PROC 0x8
#define TRACE_GRAPH_PRINT_DURATION 0x10
#define TRACE_GRAPH_PRINT_ABS_TIME 0x20
-#define TRACE_GRAPH_PRINT_IRQS 0x40
-#define TRACE_GRAPH_PRINT_TAIL 0x80
-#define TRACE_GRAPH_SLEEP_TIME 0x100
-#define TRACE_GRAPH_GRAPH_TIME 0x200
+#define TRACE_GRAPH_PRINT_REL_TIME 0x40
+#define TRACE_GRAPH_PRINT_IRQS 0x80
+#define TRACE_GRAPH_PRINT_TAIL 0x100
+#define TRACE_GRAPH_SLEEP_TIME 0x200
+#define TRACE_GRAPH_GRAPH_TIME 0x400
#define TRACE_GRAPH_PRINT_FILL_SHIFT 28
#define TRACE_GRAPH_PRINT_FILL_MASK (0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT)

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index c2af1560e856..16ebbdd7b22e 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -500,6 +500,17 @@ static void print_graph_abs_time(u64 t, struct trace_seq *s)
(unsigned long)t, usecs_rem);
}

+static void
+print_graph_rel_time(struct trace_iterator *iter, struct trace_seq *s)
+{
+ unsigned long long usecs;
+
+ usecs = iter->ts - iter->trace_buffer->time_start;
+ do_div(usecs, NSEC_PER_USEC);
+
+ trace_seq_printf(s, "%9llu us | ", usecs);
+}
+
static void
print_graph_irq(struct trace_iterator *iter, unsigned long addr,
enum trace_type type, int cpu, pid_t pid, u32 flags)
@@ -517,6 +528,10 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
print_graph_abs_time(iter->ts, s);

+ /* Relative time */
+ if (flags & TRACE_GRAPH_PRINT_REL_TIME)
+ print_graph_rel_time(iter, s);
+
/* Cpu */
if (flags & TRACE_GRAPH_PRINT_CPU)
print_graph_cpu(s, cpu);
@@ -725,6 +740,10 @@ print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
print_graph_abs_time(iter->ts, s);

+ /* Relative time */
+ if (flags & TRACE_GRAPH_PRINT_REL_TIME)
+ print_graph_rel_time(iter, s);
+
/* Cpu */
if (flags & TRACE_GRAPH_PRINT_CPU)
print_graph_cpu(s, cpu);
@@ -1101,6 +1120,8 @@ static void print_lat_header(struct seq_file *s, u32 flags)

if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
size += 16;
+ if (flags & TRACE_GRAPH_PRINT_REL_TIME)
+ size += 16;
if (flags & TRACE_GRAPH_PRINT_CPU)
size += 4;
if (flags & TRACE_GRAPH_PRINT_PROC)
@@ -1125,6 +1146,8 @@ static void __print_graph_headers_flags(struct trace_array *tr,
seq_putc(s, '#');
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
seq_puts(s, " TIME ");
+ if (flags & TRACE_GRAPH_PRINT_REL_TIME)
+ seq_puts(s, " REL TIME ");
if (flags & TRACE_GRAPH_PRINT_CPU)
seq_puts(s, " CPU");
if (flags & TRACE_GRAPH_PRINT_PROC)
@@ -1139,6 +1162,8 @@ static void __print_graph_headers_flags(struct trace_array *tr,
seq_putc(s, '#');
if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
seq_puts(s, " | ");
+ if (flags & TRACE_GRAPH_PRINT_REL_TIME)
+ seq_puts(s, " | ");
if (flags & TRACE_GRAPH_PRINT_CPU)
seq_puts(s, " | ");
if (flags & TRACE_GRAPH_PRINT_PROC)
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index d3294721f119..e6a62e7c6b69 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -238,7 +238,7 @@ static void irqsoff_trace_close(struct trace_iterator *iter)

#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
TRACE_GRAPH_PRINT_PROC | \
- TRACE_GRAPH_PRINT_ABS_TIME | \
+ TRACE_GRAPH_PRINT_REL_TIME | \
TRACE_GRAPH_PRINT_DURATION)

static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 4ea7e6845efb..b6c5fa10347e 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -180,7 +180,7 @@ static void wakeup_trace_close(struct trace_iterator *iter)
}

#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
- TRACE_GRAPH_PRINT_ABS_TIME | \
+ TRACE_GRAPH_PRINT_REL_TIME | \
TRACE_GRAPH_PRINT_DURATION)

static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
--
2.17.1
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