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Subject[PATCH 06/44] perf script: Support relative time
Date
From: Andi Kleen <ak@linux.intel.com>

When comparing time stamps in 'perf script' traces it can be annoying to
work with the full perf time stamps.

Add a --reltime option that displays time stamps relative to the trace
start to make it easier to read the traces.

Note: not currently supported for --time. Report an error in this
case.

Before:

% perf script
swapper 0 [000] 245402.891216: 1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
swapper 0 [000] 245402.891223: 1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
swapper 0 [000] 245402.891227: 5 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
swapper 0 [000] 245402.891231: 41 cycles:ppp: ffffffffa0068816 native_write_msr+0x6 ([kernel.kallsyms])
swapper 0 [000] 245402.891235: 355 cycles:ppp: ffffffffa000dd51 intel_bts_enable_local+0x21 ([kernel.kallsyms])
swapper 0 [000] 245402.891239: 3084 cycles:ppp: ffffffffa0a0150a end_repeat_nmi+0x48 ([kernel.kallsyms])

After:

% perf script --reltime

swapper 0 [000] 0.000000: 1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
swapper 0 [000] 0.000006: 1 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
swapper 0 [000] 0.000010: 5 cycles:ppp: ffffffffa0068814 native_write_msr+0x4 ([kernel.kallsyms])
swapper 0 [000] 0.000014: 41 cycles:ppp: ffffffffa0068816 native_write_msr+0x6 ([kernel.kallsyms])
swapper 0 [000] 0.000018: 355 cycles:ppp: ffffffffa000dd51 intel_bts_enable_local+0x21 ([kernel.kallsyms])
swapper 0 [000] 0.000022: 3084 cycles:ppp: ffffffffa0a0150a end_repeat_nmi+0x48 ([kernel.kallsyms])

Committer notes:

Do not use 'time' as the name of a variable, as this breaks the build on
older glibcs:

cc1: warnings being treated as errors
builtin-script.c: In function 'perf_sample__fprintf_start':
builtin-script.c:691: warning: declaration of 'time' shadows a global declaration
/usr/include/time.h:187: warning: shadowed declaration is here

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
LPU-Reference: 20190314225002.30108-8-andi@firstfloor.org
Link: https://lkml.kernel.org/n/tip-bpahyi6pr9r399mvihu65fvc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-script.txt | 3 +++
tools/perf/builtin-script.c | 18 ++++++++++++++++--
2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 2e19fd7ffe35..9b0d04dd2a61 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -380,6 +380,9 @@ include::itrace.txt[]
Set the maximum number of program blocks to print with brstackasm for
each sample.

+--reltime::
+ Print time stamps relative to trace start.
+
--per-event-dump::
Create per event files with a "perf.data.EVENT.dump" name instead of
printing to stdout, useful, for instance, for generating flamegraphs.
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 2f93d60c5a17..61cfd8f70989 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -53,6 +53,8 @@

static char const *script_name;
static char const *generate_script_lang;
+static bool reltime;
+static u64 initial_time;
static bool debug_mode;
static u64 last_timestamp;
static u64 nr_unordered;
@@ -686,7 +688,13 @@ static int perf_sample__fprintf_start(struct perf_sample *sample,
}

if (PRINT_FIELD(TIME)) {
- nsecs = sample->time;
+ u64 t = sample->time;
+ if (reltime) {
+ if (!initial_time)
+ initial_time = sample->time;
+ t = sample->time - initial_time;
+ }
+ nsecs = t;
secs = nsecs / NSEC_PER_SEC;
nsecs -= secs * NSEC_PER_SEC;

@@ -694,7 +702,7 @@ static int perf_sample__fprintf_start(struct perf_sample *sample,
printed += fprintf(fp, "%5lu.%09llu: ", secs, nsecs);
else {
char sample_time[32];
- timestamp__scnprintf_usec(sample->time, sample_time, sizeof(sample_time));
+ timestamp__scnprintf_usec(t, sample_time, sizeof(sample_time));
printed += fprintf(fp, "%12s: ", sample_time);
}
}
@@ -3413,6 +3421,7 @@ int cmd_script(int argc, const char **argv)
"Set the maximum stack depth when parsing the callchain, "
"anything beyond the specified depth will be ignored. "
"Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
+ OPT_BOOLEAN(0, "reltime", &reltime, "Show time stamps relative to start"),
OPT_BOOLEAN('I', "show-info", &show_full_info,
"display extended information from perf.data file"),
OPT_BOOLEAN('\0', "show-kernel-path", &symbol_conf.show_kernel_path,
@@ -3487,6 +3496,11 @@ int cmd_script(int argc, const char **argv)
}
}

+ if (script.time_str && reltime) {
+ fprintf(stderr, "Don't combine --reltime with --time\n");
+ return -1;
+ }
+
if (itrace_synth_opts.callchain &&
itrace_synth_opts.callchain_sz > scripting_max_stack)
scripting_max_stack = itrace_synth_opts.callchain_sz;
--
2.20.1
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