perf report: Implement browsing of individual samples

Now 'perf report' can show whole time periods with 'perf script', but
the user still has to find individual samples of interest manually.

It would be expensive and complicated to search for the right samples in
the whole perf file. Typically users only need to look at a small number
of samples for useful analysis.

Also the full scripts tend to show samples of all CPUs and all threads
mixed up, which can be very confusing on larger systems.

Add a new --samples option to save a small random number of samples per
hist entry.

Use a reservoir sample technique to select a representatve number of
samples.

Then allow browsing the samples using 'perf script' as part of the hist
entry context menu. This automatically adds the right filters, so only
the thread or cpu of the sample is displayed. Then we use less' search
functionality to directly jump the to the time stamp of the selected
sample.

It uses different menus for assembler and source display.  Assembler
needs xed installed and source needs debuginfo.

Currently it only supports as many samples as fit on the screen due to
some limitations in the slang ui code.

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>
Link: http://lkml.kernel.org/r/20190311174605.GA29294@tassilo.jf.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/tools/perf/ui/browsers/res_sample.c b/tools/perf/ui/browsers/res_sample.c
new file mode 100644
index 0000000000000..884ef2a92c150
--- /dev/null
+++ b/tools/perf/ui/browsers/res_sample.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Display a menu with individual samples to browse with perf script */
+#include "util.h"
+#include "hist.h"
+#include "evsel.h"
+#include "hists.h"
+#include "sort.h"
+#include "config.h"
+#include "time-utils.h"
+#include <linux/time64.h>
+
+static u64 context_len = 10 * NSEC_PER_MSEC;
+
+static int res_sample_config(const char *var, const char *value, void *data __maybe_unused)
+{
+	if (!strcmp(var, "samples.context"))
+		return perf_config_u64(&context_len, var, value);
+	return 0;
+}
+
+void res_sample_init(void)
+{
+	perf_config(res_sample_config, NULL);
+}
+
+int res_sample_browse(struct res_sample *res_samples, int num_res,
+		      struct perf_evsel *evsel, enum rstype rstype)
+{
+	char **names;
+	int i, n;
+	int choice;
+	char *cmd;
+	char pbuf[256], tidbuf[32], cpubuf[32];
+	const char *perf = perf_exe(pbuf, sizeof pbuf);
+	char trange[128], tsample[64];
+	struct res_sample *r;
+	char extra_format[256];
+
+	/* For now since ui__popup_menu doesn't like lists that don't fit */
+	num_res = max(min(SLtt_Screen_Rows - 4, num_res), 0);
+
+	names = calloc(num_res, sizeof(char *));
+	if (!names)
+		return -1;
+	for (i = 0; i < num_res; i++) {
+		char tbuf[64];
+
+		timestamp__scnprintf_nsec(res_samples[i].time, tbuf, sizeof tbuf);
+		if (asprintf(&names[i], "%s: CPU %d tid %d", tbuf,
+			     res_samples[i].cpu, res_samples[i].tid) < 0) {
+			while (--i >= 0)
+				free(names[i]);
+			free(names);
+			return -1;
+		}
+	}
+	choice = ui__popup_menu(num_res, names);
+	for (i = 0; i < num_res; i++)
+		free(names[i]);
+	free(names);
+
+	if (choice < 0 || choice >= num_res)
+		return -1;
+	r = &res_samples[choice];
+
+	n = timestamp__scnprintf_nsec(r->time - context_len, trange, sizeof trange);
+	trange[n++] = ',';
+	timestamp__scnprintf_nsec(r->time + context_len, trange + n, sizeof trange - n);
+
+	timestamp__scnprintf_nsec(r->time, tsample, sizeof tsample);
+
+	attr_to_script(extra_format, &evsel->attr);
+
+	if (asprintf(&cmd, "%s script %s%s --time %s %s%s %s%s --ns %s %s %s %s %s | less +/%s",
+		     perf,
+		     input_name ? "-i " : "",
+		     input_name ? input_name : "",
+		     trange,
+		     r->cpu >= 0 ? "--cpu " : "",
+		     r->cpu >= 0 ? (sprintf(cpubuf, "%d", r->cpu), cpubuf) : "",
+		     r->tid ? "--tid " : "",
+		     r->tid ? (sprintf(tidbuf, "%d", r->tid), tidbuf) : "",
+		     extra_format,
+		     rstype == A_ASM ? "-F +insn --xed" :
+		     rstype == A_SOURCE ? "-F +srcline,+srccode" : "",
+		     symbol_conf.inline_name ? "--inline" : "",
+		     "--show-lost-events ",
+		     r->tid ? "--show-switch-events --show-task-events " : "",
+		     tsample) < 0)
+		return -1;
+	run_script(cmd);
+	free(cmd);
+	return 0;
+}