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Subject[PATCH RFC 3/3] perf script: Add callindent option
Date
Based on patches from Andi Kleen.

When printing PT instruction traces with perf script it is rather useful to
see some indentation for the call tree. This patch adds a new callindent
field to perf script that prints spaces for the function call stack depth.

We already have code to track the function call stack for PT, that we can
reuse with minor modifications.

The resulting output is not quite as nice as ftrace yet, but a lot better
than what was there before.

Note there are some corner cases when the thread stack gets code confused
and prints incorrect indentation. Even with that it is fairly useful.

When displaying kernel code traces it is recommended to run as root, as
otherwise perf doesn't understand the kernel addresses properly, and may
not reset the call stack correctly on kernel boundaries.

Example output:

sudo perf-with-kcore record eg2 -a -e intel_pt// -- sleep 1
sudo perf-with-kcore script eg2 --ns -F callindent,time,comm,pid,sym,ip,addr,event,cpu --itrace=cre | less
...
swapper 0 [000] 21191.973043157: branches: call irq_exit ffffffff8104e880 smp_call_function_single_interrupt+0x30 => ffffffff8107f2b0 irq_exit
swapper 0 [000] 21191.973043157: branches: call idle_cpu ffffffff8107f2f9 irq_exit+0x49 => ffffffff810a5890 idle_cpu
swapper 0 [000] 21191.973043157: branches: ret idle_cpu ffffffff810a58d7 idle_cpu+0x47 => ffffffff8107f2fe irq_exit
swapper 0 [000] 21191.973043157: branches: call tick_nohz_irq_exit ffffffff8107f34d irq_exit+0x9d => ffffffff810f4850 tick_nohz_irq_exit
swapper 0 [000] 21191.973043157: branches: call __tick_nohz_idle_enter ffffffff810f4870 tick_nohz_irq_exit+0x20 => ffffffff810f4160 __tick_nohz_idle_enter
swapper 0 [000] 21191.973043157: branches: call ktime_get ffffffff810f4181 __tick_nohz_idle_enter+0x21 => ffffffff810eb750 ktime_get
swapper 0 [000] 21191.973043157: branches: call read_tsc ffffffff810eb786 ktime_get+0x36 => ffffffff810362e0 read_tsc
swapper 0 [000] 21191.973043157: branches: ret read_tsc ffffffff810362f4 read_tsc+0x14 => ffffffff810eb78c ktime_get
swapper 0 [000] 21191.973043157: branches: ret ktime_get ffffffff810eb7d6 ktime_get+0x86 => ffffffff810f4186 __tick_nohz_idle_enter
swapper 0 [000] 21191.973043157: branches: call sched_clock_idle_sleep_event ffffffff810f419b __tick_nohz_idle_enter+0x3b => ffffffff810a9220 sched_clock_idle_sleep_event
swapper 0 [000] 21191.973043157: branches: call sched_clock_cpu ffffffff810a922b sched_clock_idle_sleep_event+0xb => ffffffff810a9180 sched_clock_cpu
swapper 0 [000] 21191.973043157: branches: call sched_clock ffffffff810a91ed sched_clock_cpu+0x6d => ffffffff810369d0 sched_clock
swapper 0 [000] 21191.973043157: branches: call native_sched_clock ffffffff810369d4 sched_clock+0x4 => ffffffff810368c0 native_sched_clock
swapper 0 [000] 21191.973043157: branches: ret native_sched_clock ffffffff8103690c native_sched_clock+0x4c => ffffffff810369d9 sched_clock
swapper 0 [000] 21191.973043157: branches: ret sched_clock ffffffff810369dc sched_clock+0xc => ffffffff810a91f2 sched_clock_cpu
swapper 0 [000] 21191.973043157: branches: ret sched_clock_cpu ffffffff810a91f6 sched_clock_cpu+0x76 => ffffffff810a9230 sched_clock_idle_sleep_event
swapper 0 [000] 21191.973043157: branches: ret sched_clock_idle_sleep_event ffffffff810a9231 sched_clock_idle_sleep_event+0x11 => ffffffff810f41a0 __tick_nohz_idle_enter

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/Documentation/perf-script.txt | 6 +++
tools/perf/builtin-script.c | 70 ++++++++++++++++++++++++++++++++
tools/perf/util/thread-stack.c | 7 ++++
tools/perf/util/thread-stack.h | 1 +
4 files changed, 84 insertions(+)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 4f34379ebd77..576a85c16f4c 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -172,6 +172,12 @@ OPTIONS
transaction abort, trace begin, trace end, and in transaction,
respectively.

+ The callindent field is synthesized and may have a value when
+ Instruction Trace decoding. For calls and returns, it will display the
+ name of the symbol indented with spaces to reflect the stack depth. To
+ differentiate: calls are prefixed by "call", returns by "ret", trace
+ start by "strt" and trace end by "end".
+
Finally, a user may not set fields to none for all event types.
i.e., -F "" is not allowed.

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 46011235af5d..05e088560c44 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -21,6 +21,7 @@
#include "util/cpumap.h"
#include "util/thread_map.h"
#include "util/stat.h"
+#include "util/thread-stack.h"
#include <linux/bitmap.h>
#include <linux/stringify.h>
#include "asm/bug.h"
@@ -63,6 +64,7 @@ enum perf_output_field {
PERF_OUTPUT_DATA_SRC = 1U << 17,
PERF_OUTPUT_WEIGHT = 1U << 18,
PERF_OUTPUT_BPF_OUTPUT = 1U << 19,
+ PERF_OUTPUT_CALLINDENT = 1U << 20,
};

struct output_option {
@@ -89,6 +91,7 @@ struct output_option {
{.str = "data_src", .field = PERF_OUTPUT_DATA_SRC},
{.str = "weight", .field = PERF_OUTPUT_WEIGHT},
{.str = "bpf-output", .field = PERF_OUTPUT_BPF_OUTPUT},
+ {.str = "callindent", .field = PERF_OUTPUT_CALLINDENT},
};

/* default set to maintain compatibility with current format */
@@ -562,6 +565,70 @@ static void print_sample_addr(struct perf_sample *sample,
}
}

+static void print_sample_callindent(struct perf_sample *sample,
+ struct perf_evsel *evsel,
+ struct thread *thread,
+ struct addr_location *al)
+{
+ struct perf_event_attr *attr = &evsel->attr;
+ size_t depth = thread_stack__depth(thread);
+ const char *prefix = NULL, *name = NULL;
+ struct addr_location addr_al;
+ static int spacing;
+ int len = 0;
+ u64 ip = 0;
+
+ /*
+ * The 'return' has already been popped off the stack so the depth has
+ * to be adjusted to match the 'call'.
+ */
+ if (thread->ts && sample->flags & PERF_IP_FLAG_RETURN)
+ depth += 1;
+
+ if (sample->flags & (PERF_IP_FLAG_CALL | PERF_IP_FLAG_TRACE_BEGIN)) {
+ if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN)
+ prefix = "strt";
+ else
+ prefix = "call";
+ if (sample_addr_correlates_sym(attr)) {
+ thread__resolve(thread, &addr_al, sample);
+ if (addr_al.sym)
+ name = addr_al.sym->name;
+ else
+ ip = sample->addr;
+ } else {
+ ip = sample->addr;
+ }
+ } else if (sample->flags & (PERF_IP_FLAG_RETURN | PERF_IP_FLAG_TRACE_END)) {
+ if (sample->flags & PERF_IP_FLAG_TRACE_END)
+ prefix = "end";
+ else
+ prefix = "ret";
+ if (al->sym)
+ name = al->sym->name;
+ else
+ ip = sample->ip;
+ }
+
+ if (name)
+ len = printf("%*s%-4s %s", (int)depth * 4, "", prefix, name);
+ else if (prefix)
+ len = printf("%*s%-4s %16" PRIx64, (int)depth * 4, "", prefix, ip);
+
+ if (len < 0)
+ return;
+
+ /*
+ * Try to keep the output length from changing frequently so that the
+ * output lines up more nicely.
+ */
+ if (len > spacing || (len && len < spacing - 52))
+ spacing = round_up(len + 4, 32);
+
+ if (len < spacing)
+ printf("%*s", spacing - len, "");
+}
+
static void print_sample_bts(struct perf_sample *sample,
struct perf_evsel *evsel,
struct thread *thread,
@@ -2259,6 +2326,9 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
script.session = session;
script__setup_sample_type(&script);

+ if (output[PERF_TYPE_HARDWARE].fields & PERF_OUTPUT_CALLINDENT)
+ itrace_synth_opts.thread_stack = true;
+
session->itrace_synth_opts = &itrace_synth_opts;

if (cpu_list) {
diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index 825086aa9a08..d3301529f6a7 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -616,3 +616,10 @@ int thread_stack__process(struct thread *thread, struct comm *comm,

return err;
}
+
+size_t thread_stack__depth(struct thread *thread)
+{
+ if (!thread->ts)
+ return 0;
+ return thread->ts->cnt;
+}
diff --git a/tools/perf/util/thread-stack.h b/tools/perf/util/thread-stack.h
index ad44c7944b8e..b7e41c4ebfdd 100644
--- a/tools/perf/util/thread-stack.h
+++ b/tools/perf/util/thread-stack.h
@@ -87,6 +87,7 @@ void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
size_t sz, u64 ip);
int thread_stack__flush(struct thread *thread);
void thread_stack__free(struct thread *thread);
+size_t thread_stack__depth(struct thread *thread);

struct call_return_processor *
call_return_processor__new(int (*process)(struct call_return *cr, void *data),
--
1.9.1
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