perf diff: Support --cpu filter option

To improve 'perf diff', implement a --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>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1551791143-10334-3-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index 036d65b..8c2c229 100644 (file)
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -163,6 +163,11 @@ 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 17cd898..dfe6c76 100644 (file)
--- 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;
@@ -892,6 +900,13 @@ static int __cmd_diff(void)
                                goto out_delete;
                }
 
+               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.path);
@@ -969,6 +984,7 @@ 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()
 };