[PATCH v1 2/3] perf diff: Support --cpu filter option

Jin Yao
2019-02-25T05:52:15Z

For better support for perf diff, it would be useful to add --cpu filter
option.

Multiple CPUs can be provided as a comma-separated list with no space: 0,1.
Ranges of CPUs are specified with -: 0-2. Default is to report samples on
all CPUs.

For example,

perf diff --cpu 0,1

It only diff the samples for CPU0 and CPU1.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
tools/perf/Documentation/perf-diff.txt | 5 +++++
tools/perf/builtin-diff.c | 16 ++++++++++++++++
2 files changed, 21 insertions(+)

diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index 5bfe876..ed13b3f 100644
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -159,6 +159,11 @@ OPTIONS
the end of perf.data.old and analyzes the perf.data from the
timestamp 3971.150589 to the end of perf.data.

+--cpu:: Only diff samples for the list of CPUs provided. Multiple CPUs can
+ be provided as a comma-separated list with no space: 0,1. Ranges of
+ CPUs are specified with -: 0-2. Default is to report samples on all
+ CPUs.
+
COMPARISON
----------
The comparison is governed by the baseline file. The baseline perf.data
diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index ddc41e7..319fbc9 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -83,6 +83,9 @@ static unsigned int sort_compute = 1;
static s64 compute_wdiff_w1;
static s64 compute_wdiff_w2;

+static const char *cpu_list;
+static DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
+
enum {
COMPUTE_DELTA,
COMPUTE_RATIO,
@@ -354,6 +357,11 @@ static int diff__process_sample_event(struct perf_tool *tool,
return -1;
}

+ if (cpu_list && !test_bit(sample->cpu, cpu_bitmap)) {
+ ret = 0;
+ goto out_put;
+ }
+
if (!hists__add_entry(hists, &al, NULL, NULL, NULL, sample, true)) {
pr_warning("problem incrementing symbol period, skipping event\n");
goto out_put;
@@ -905,6 +913,13 @@ static int __cmd_diff(void)
pdiff.range_num = 1;
}

+ if (cpu_list) {
+ ret = perf_session__cpu_bitmap(d->session, cpu_list,
+ cpu_bitmap);
+ if (ret < 0)
+ goto out_delete;
+ }
+
ret = perf_session__process_events(d->session);
if (ret) {
pr_err("Failed to process %s\n", d->data.file.path);
@@ -977,6 +992,7 @@ static const struct option options[] = {
"How to display percentage of filtered entries", parse_filter_percentage),
OPT_STRING(0, "time", &pdiff.time_str, "str",
"Time span (time percent or absolute timestamp)"),
+ OPT_STRING(0, "cpu", &cpu_list, "cpu", "list of cpus to profile"),
OPT_END()
};

--
2.7.4