Re: [PATCH v2] perf diff: Report noisy for cycles diff

From: Jin, Yao
Date: Mon Aug 05 2019 - 20:16:14 EST

Hi,

Any comments for this version?

Thanks
Jin Yao

On 7/25/2019 6:14 AM, Jin Yao wrote:
This patch prints the stddev and hist for the cycles diff of
program block. It can help us to understand if the cycles diff
is noisy or not.

This patch is inspired by Andi Kleen's patch
https://lwn.net/Articles/600471/

We create new option '-n or --noisy'.

Example:

perf record -b ./div
perf record -b ./div
perf diff -c cycles

# Event 'cycles'
#
# Baseline [Program Block Range] Cycles Diff Shared Object Symbol
# ........ ...................................................................... ................. ................................
#
46.42% [div.c:40 -> div.c:40] 0 div [.] main
46.42% [div.c:42 -> div.c:44] 0 div [.] main
46.42% [div.c:42 -> div.c:39] 0 div [.] main
20.72% [random_r.c:357 -> random_r.c:394] -2 libc-2.27.so [.] __random_r
20.72% [random_r.c:357 -> random_r.c:380] -1 libc-2.27.so [.] __random_r
20.72% [random_r.c:388 -> random_r.c:388] 0 libc-2.27.so [.] __random_r
20.72% [random_r.c:388 -> random_r.c:391] 0 libc-2.27.so [.] __random_r
17.58% [random.c:288 -> random.c:291] 0 libc-2.27.so [.] __random
17.58% [random.c:291 -> random.c:291] 0 libc-2.27.so [.] __random
17.58% [random.c:293 -> random.c:293] 0 libc-2.27.so [.] __random
17.58% [random.c:295 -> random.c:295] 0 libc-2.27.so [.] __random
17.58% [random.c:295 -> random.c:295] 0 libc-2.27.so [.] __random
17.58% [random.c:298 -> random.c:298] 0 libc-2.27.so [.] __random
8.33% [div.c:22 -> div.c:25] 0 div [.] compute_flag
8.33% [div.c:27 -> div.c:28] 0 div [.] compute_flag
4.80% [rand.c:26 -> rand.c:27] 0 libc-2.27.so [.] rand
4.80% [rand.c:28 -> rand.c:28] 0 libc-2.27.so [.] rand
2.14% [rand@plt+0 -> rand@plt+0] 0 div [.] rand@plt

When we enable the option '-n' or '--noisy', the output is

perf diff -c cycles -n

# Event 'cycles'
#
# Baseline [Program Block Range]/Cycles Diff/stddev/Hist Shared Object Symbol
# ........ ................................................................................ ................. ................................
#
46.42% [div.c:40 -> div.c:40] 0 Â 40.2% ââââââââ div [.] main
46.42% [div.c:42 -> div.c:44] 0 Â100.0% ââââââââ div [.] main
46.42% [div.c:42 -> div.c:39] 0 Â 15.3% ââââââââ div [.] main
20.72% [random_r.c:357 -> random_r.c:394] -2 Â 20.1% ââââââââ libc-2.27.so [.] __random_r
20.72% [random_r.c:357 -> random_r.c:380] -1 Â 20.9% ââââââââ libc-2.27.so [.] __random_r
20.72% [random_r.c:388 -> random_r.c:388] 0 Â 0.0% libc-2.27.so [.] __random_r
20.72% [random_r.c:388 -> random_r.c:391] 0 Â 88.0% ââââââââ libc-2.27.so [.] __random_r
17.58% [random.c:288 -> random.c:291] 0 Â 29.3% ââââââââ libc-2.27.so [.] __random
17.58% [random.c:291 -> random.c:291] 0 Â 29.3% ââââââââ libc-2.27.so [.] __random
17.58% [random.c:293 -> random.c:293] 0 Â 29.3% ââââââââ libc-2.27.so [.] __random
17.58% [random.c:295 -> random.c:295] 0 Â 0.0% libc-2.27.so [.] __random
17.58% [random.c:295 -> random.c:295] 0 Â 0.0% libc-2.27.so [.] __random
17.58% [random.c:298 -> random.c:298] 0 Â 0.0% libc-2.27.so [.] __random
8.33% [div.c:22 -> div.c:25] 0 Â 29.3% ââââââââ div [.] compute_flag
8.33% [div.c:27 -> div.c:28] 0 Â 48.8% ââââââââ div [.] compute_flag
4.80% [rand.c:26 -> rand.c:27] 0 Â 29.3% ââââââââ libc-2.27.so [.] rand
4.80% [rand.c:28 -> rand.c:28] 0 Â 0.0% libc-2.27.so [.] rand
2.14% [rand@plt+0 -> rand@plt+0] 0 Â 0.0% div [.] rand@plt

v2:
---
Jiri got a compile error,

CC builtin-diff.o
builtin-diff.c: In function âcompute_cycles_diffâ:
builtin-diff.c:712:10: error: taking the absolute value of unsigned type âu64â {aka âlong unsigned intâ} has no effect [-Werror=absolute-value]
712 | labs(pair->block_info->cycles_spark[i] -
| ^~~~

Because the result of u64 - u64 is still u64. Now we change the type of
cycles_spark[] to s64.

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
tools/perf/Documentation/perf-diff.txt | 5 ++
tools/perf/builtin-diff.c | 94 +++++++++++++++++++++++---
tools/perf/util/Build | 1 +
tools/perf/util/annotate.c | 4 ++
tools/perf/util/annotate.h | 2 +
tools/perf/util/sort.h | 2 +
tools/perf/util/spark.c | 35 ++++++++++
tools/perf/util/spark.h | 6 ++
tools/perf/util/stat.c | 37 ++++++++++
tools/perf/util/stat.h | 10 +++
tools/perf/util/symbol.h | 2 +
11 files changed, 187 insertions(+), 11 deletions(-)
create mode 100644 tools/perf/util/spark.c
create mode 100644 tools/perf/util/spark.h

diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index d5cc15e651cf..d9112f201a0d 100644
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -95,6 +95,11 @@ OPTIONS
diff.compute config option. See COMPARISON METHODS section for
more info.
+-n::
+--noisy::
+ Show cycles noisy data, such as stddev and hists. Should use
+ with '-c cycles'.
+
-p::
--period::
Show period values for both compared hist entries.
diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index e91c0d798181..43ac0ed06679 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -48,6 +48,7 @@ enum {
PERF_HPP_DIFF__FORMULA,
PERF_HPP_DIFF__DELTA_ABS,
PERF_HPP_DIFF__CYCLES,
+ PERF_HPP_DIFF__CYCLES_NOISY,
PERF_HPP_DIFF__MAX_INDEX
};
@@ -82,6 +83,7 @@ static bool force;
static bool show_period;
static bool show_formula;
static bool show_baseline_only;
+static bool show_noisy;
static unsigned int sort_compute = 1;
static s64 compute_wdiff_w1;
@@ -159,6 +161,10 @@ static struct header_column {
[PERF_HPP_DIFF__CYCLES] = {
.name = "[Program Block Range] Cycles Diff",
.width = 70,
+ },
+ [PERF_HPP_DIFF__CYCLES_NOISY] = {
+ .name = "[Program Block Range]/Cycles Diff/stddev/Hist",
+ .width = 80,
}
};
@@ -605,6 +611,9 @@ static void init_block_info(struct block_info *bi, struct symbol *sym,
bi->cycles_aggr = ch->cycles_aggr;
bi->num = ch->num;
bi->num_aggr = ch->num_aggr;
+
+ memcpy(bi->cycles_spark, ch->cycles_spark,
+ NUM_SPARK_VALS * sizeof(u64));
}
static int process_block_per_sym(struct hist_entry *he)
@@ -692,6 +701,17 @@ static void compute_cycles_diff(struct hist_entry *he,
pair->diff.cycles =
pair->block_info->cycles_aggr / pair->block_info->num_aggr -
he->block_info->cycles_aggr / he->block_info->num_aggr;
+
+ init_stats(&pair->diff.stats);
+
+ for (int i = 0; i < pair->block_info->num; i++) {
+ if (i >= he->block_info->num || i >= NUM_SPARK_VALS)
+ break;
+
+ update_stats(&pair->diff.stats,
+ labs(pair->block_info->cycles_spark[i] -
+ he->block_info->cycles_spark[i]));
+ }
}
}
@@ -1250,6 +1270,8 @@ static const struct option options[] = {
"Show period values."),
OPT_BOOLEAN('F', "formula", &show_formula,
"Show formula."),
+ OPT_BOOLEAN('n', "noisy", &show_noisy,
+ "Show cycles noisy - WARNING: use only with -c cycles."),
OPT_BOOLEAN('D', "dump-raw-trace", &dump_trace,
"dump raw trace in ASCII"),
OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
@@ -1322,14 +1344,17 @@ static int hpp__entry_baseline(struct hist_entry *he, char *buf, size_t size)
}
static int cycles_printf(struct hist_entry *he, struct hist_entry *pair,
- struct perf_hpp *hpp, int width)
+ struct perf_hpp *hpp, int width __maybe_unused)
{
struct block_hist *bh = container_of(he, struct block_hist, he);
struct block_hist *bh_pair = container_of(pair, struct block_hist, he);
struct hist_entry *block_he;
struct block_info *bi;
- char buf[128];
+ char buf[128], spark[32];
char *start_line, *end_line;
+ int ret = 0, pad;
+ char pfmt[20] = " ";
+ double d;
block_he = hists__get_entry(&bh_pair->block_hists, bh->block_idx);
if (!block_he) {
@@ -1350,18 +1375,56 @@ static int cycles_printf(struct hist_entry *he, struct hist_entry *pair,
end_line = map__srcline(he->ms.map, bi->sym->start + bi->end,
he->ms.sym);
- if ((start_line != SRCLINE_UNKNOWN) && (end_line != SRCLINE_UNKNOWN)) {
- scnprintf(buf, sizeof(buf), "[%s -> %s] %4ld",
- start_line, end_line, block_he->diff.cycles);
+ if (show_noisy) {
+ ret = print_stat_spark(spark, sizeof(spark),
+ &block_he->diff.stats);
+ d = rel_stddev_stats(stddev_stats(&block_he->diff.stats),
+ avg_stats(&block_he->diff.stats));
+
+ if ((start_line != SRCLINE_UNKNOWN) &&
+ (end_line != SRCLINE_UNKNOWN)) {
+ scnprintf(buf, sizeof(buf),
+ "[%s -> %s] %4ld %s%5.1f%% %s",
+ start_line, end_line, block_he->diff.cycles,
+ "\u00B1", d, spark);
+ } else {
+ scnprintf(buf, sizeof(buf),
+ "[%7lx -> %7lx] %4ld %s%5.1f%% %s",
+ bi->start, bi->end, block_he->diff.cycles,
+ "\u00B1", d, spark);
+ }
+
+ if (ret > 0) {
+ pad = 8 - ((ret - 1) / 3);
+ scnprintf(pfmt, 20, "%%%ds",
+ 81 + (2 * ((ret - 1) / 3)) - pad);
+ ret = scnprintf(hpp->buf, hpp->size, pfmt, buf);
+ if (pad > 0) {
+ ret += scnprintf(hpp->buf + ret,
+ hpp->size - ret,
+ "%-*s", pad, " ");
+ }
+ } else {
+ ret = scnprintf(hpp->buf, hpp->size, "%73s", buf);
+ ret += scnprintf(hpp->buf + ret, hpp->size - ret,
+ "%-*s", 8, " ");
+ }
} else {
- scnprintf(buf, sizeof(buf), "[%7lx -> %7lx] %4ld",
- bi->start, bi->end, block_he->diff.cycles);
+ if ((start_line != SRCLINE_UNKNOWN) &&
+ (end_line != SRCLINE_UNKNOWN)) {
+ scnprintf(buf, sizeof(buf), "[%s -> %s] %4ld",
+ start_line, end_line, block_he->diff.cycles);
+ } else {
+ scnprintf(buf, sizeof(buf), "[%7lx -> %7lx] %4ld",
+ bi->start, bi->end, block_he->diff.cycles);
+ }
+
+ ret = scnprintf(hpp->buf, hpp->size, "%*s", width, buf);
}
free_srcline(start_line);
free_srcline(end_line);
-
- return scnprintf(hpp->buf, hpp->size, "%*s", width, buf);
+ return ret;
}
static int __hpp__color_compare(struct perf_hpp_fmt *fmt,
@@ -1659,6 +1722,7 @@ static void data__hpp_register(struct data__file *d, int idx)
fmt->sort = hist_entry__cmp_delta_abs;
break;
case PERF_HPP_DIFF__CYCLES:
+ case PERF_HPP_DIFF__CYCLES_NOISY:
fmt->color = hpp__color_cycles;
fmt->sort = hist_entry__cmp_nop;
break;
@@ -1688,8 +1752,13 @@ static int ui_init(void)
* PERF_HPP_DIFF__RATIO
* PERF_HPP_DIFF__WEIGHTED_DIFF
*/
- data__hpp_register(d, i ? compute_2_hpp[compute] :
- PERF_HPP_DIFF__BASELINE);
+ if (!show_noisy) {
+ data__hpp_register(d, i ? compute_2_hpp[compute] :
+ PERF_HPP_DIFF__BASELINE);
+ } else if (compute == COMPUTE_CYCLES) {
+ data__hpp_register(d, i ? PERF_HPP_DIFF__CYCLES_NOISY :
+ PERF_HPP_DIFF__BASELINE);
+ }
/*
* And the rest:
@@ -1845,6 +1914,9 @@ int cmd_diff(int argc, const char **argv)
if (quiet)
perf_quiet_option();
+ if (show_noisy && (compute != COMPUTE_CYCLES))
+ usage_with_options(diff_usage, options);
+
symbol__annotation_init();
if (symbol__init(NULL) < 0)
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 08f670d21615..49ac5c8d0bba 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -90,6 +90,7 @@ perf-y += cloexec.o
perf-y += call-path.o
perf-y += rwsem.o
perf-y += thread-stack.o
+perf-y += spark.o
perf-$(CONFIG_AUXTRACE) += auxtrace.o
perf-$(CONFIG_AUXTRACE) += intel-pt-decoder/
perf-$(CONFIG_AUXTRACE) += intel-pt.o
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index d46f2ae2c695..c47ab902dbb6 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -847,6 +847,10 @@ static int __symbol__account_cycles(struct cyc_hist *ch,
ch[offset].start < start)
return 0;
}
+
+ if (ch[offset].num < NUM_SPARK_VALS)
+ ch[offset].cycles_spark[ch[offset].num] = cycles;
+
ch[offset].have_start = have_start;
ch[offset].start = start;
ch[offset].cycles += cycles;
diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index d94be9140e31..54ce7f3231f2 100644
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -11,6 +11,7 @@
#include <pthread.h>
#include <asm/bug.h>
#include "symbol_conf.h"
+#include "stat.h"
struct hist_browser_timer;
struct hist_entry;
@@ -235,6 +236,7 @@ struct cyc_hist {
u64 cycles_aggr;
u64 cycles_max;
u64 cycles_min;
+ s64 cycles_spark[NUM_SPARK_VALS];
u32 num;
u32 num_aggr;
u8 have_start;
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index 5e34676a98e8..267abf743ffd 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -23,6 +23,7 @@
#include "parse-events.h"
#include "hist.h"
#include "srcline.h"
+#include "stat.h"
struct thread;
@@ -83,6 +84,7 @@ struct hist_entry_diff {
/* PERF_HPP_DIFF__CYCLES */
s64 cycles;
};
+ struct stats stats;
};
struct hist_entry_ops {
diff --git a/tools/perf/util/spark.c b/tools/perf/util/spark.c
new file mode 100644
index 000000000000..25f280d547a6
--- /dev/null
+++ b/tools/perf/util/spark.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <limits.h>
+#include <string.h>
+#include <stdlib.h>
+#include "spark.h"
+#include "stat.h"
+
+#define NUM_SPARKS 8
+#define SPARK_SHIFT 8
+
+/* Print spark lines on outf for numval values in val. */
+int print_spark(char *bf, int size, unsigned long *val, int numval)
+{
+ static const char *ticks[NUM_SPARKS] = {
+ "â", "â", "â", "â", "â", "â", "â", "â"
+ };
+ int i, printed = 0;
+ unsigned long min = ULONG_MAX, max = 0, f;
+
+ for (i = 0; i < numval; i++) {
+ if (val[i] < min)
+ min = val[i];
+ if (val[i] > max)
+ max = val[i];
+ }
+ f = ((max - min) << SPARK_SHIFT) / (NUM_SPARKS - 1);
+ if (f < 1)
+ f = 1;
+ for (i = 0; i < numval; i++) {
+ printed += scnprintf(bf + printed, size - printed, "%s",
+ ticks[((val[i] - min) << SPARK_SHIFT) / f]);
+ }
+
+ return printed;
+}
diff --git a/tools/perf/util/spark.h b/tools/perf/util/spark.h
new file mode 100644
index 000000000000..19bab3adcd3a
--- /dev/null
+++ b/tools/perf/util/spark.h
@@ -0,0 +1,6 @@
+#ifndef SPARK_H
+#define SPARK_H 1
+
+int print_spark(char *bf, int size, unsigned long *val, int numval);
+
+#endif
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 799f3c0a9050..81ce99c14e52 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -6,11 +6,16 @@
#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
+#include "spark.h"
#include <linux/zalloc.h>
void update_stats(struct stats *stats, u64 val)
{
double delta;
+ int n = stats->n;
+
+ if (n < NUM_SPARK_VALS)
+ stats->svals[n] = val;
stats->n++;
delta = val - stats->mean;
@@ -24,6 +29,38 @@ void update_stats(struct stats *stats, u64 val)
stats->min = val;
}
+static int all_zero(unsigned long *vals, int len)
+{
+ int i;
+
+ for (i = 0; i < len; i++)
+ if (vals[i] != 0)
+ return 0;
+ return 1;
+}
+
+int print_stat_spark(char *bf, int size, struct stats *stat)
+{
+ int len, printed;
+
+ if (stat->n <= 1)
+ return 0;
+
+ len = stat->n;
+ if (len > NUM_SPARK_VALS)
+ len = NUM_SPARK_VALS;
+ if (all_zero(stat->svals, len))
+ return 0;
+
+ printed = print_spark(bf, size, stat->svals, len);
+ printed += scnprintf(bf + printed, size - printed, " ");
+
+ if (stat->n > NUM_SPARK_VALS)
+ printed += scnprintf(bf + printed, size - printed, "..");
+
+ return printed;
+}
+
double avg_stats(struct stats *stats)
{
return stats->mean;
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 95b4de7a9d51..3448d319a220 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -8,14 +8,18 @@
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
+#include <stdio.h>
#include "xyarray.h"
#include "rblist.h"
#include "perf.h"
#include "event.h"
+#define NUM_SPARK_VALS 8 /* support spark line on first N items */
+
struct stats {
double n, mean, M2;
u64 max, min;
+ unsigned long svals[NUM_SPARK_VALS];
};
enum perf_stat_evsel_id {
@@ -134,13 +138,19 @@ double avg_stats(struct stats *stats);
double stddev_stats(struct stats *stats);
double rel_stddev_stats(double stddev, double avg);
+int print_stat_spark(char *bf, int size, struct stats *stat);
+
static inline void init_stats(struct stats *stats)
{
+ int i;
+
stats->n = 0.0;
stats->mean = 0.0;
stats->M2 = 0.0;
stats->min = (u64) -1;
stats->max = 0;
+ for (i = 0; i < NUM_SPARK_VALS; i++)
+ stats->svals[i] = 0;
}
struct evsel;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 12755b42ea93..3b8212f0a738 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -12,6 +12,7 @@
#include "branch.h"
#include "path.h"
#include "symbol_conf.h"
+#include "stat.h"
#ifdef HAVE_LIBELF_SUPPORT
#include <libelf.h>
@@ -137,6 +138,7 @@ struct block_info {
u64 end;
u64 cycles;
u64 cycles_aggr;
+ s64 cycles_spark[NUM_SPARK_VALS];
int num;
int num_aggr;
refcount_t refcnt;