perf report: Auto-detect branch stack sampling mode

This patch enhances perf report to auto-detect when the
perf.data file contains samples with branch stacks. That way it
is not necessary to use the -b option.

To force branch view mode to off, simply use --no-branch-stack.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: acme@redhat.com
Cc: asharma@fb.com
Cc: ravitillo@lbl.gov
Cc: vweaver1@eecs.utk.edu
Cc: khandual@linux.vnet.ibm.com
Cc: dsahern@gmail.com
Link: http://lkml.kernel.org/r/1331246868-19905-4-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 41 insertions, 20 deletions

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 19b9092cf8b7..87feeee8b90c 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -157,8 +157,11 @@ OPTIONS
 --branch-stack::
         Use the addresses of sampled taken branches instead of the instruction
         address to build the histograms. To generate meaningful output, the
-        perf.data file must have been obtained using perf record -b xxx where
-        xxx is a branch filter option.
+        perf.data file must have been obtained using perf record -b or
+        perf record --branch-filter xxx where xxx is a branch filter option.
+        perf report is able to auto-detect whether a perf.data file contains
+        branch stacks and it will automatically switch to the branch view mode,
+        unless --no-branch-stack is used.
 
 SEE ALSO
 --------
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 528789f6c702..66e852376a05 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -170,7 +170,7 @@ static int process_sample_event(struct perf_tool *tool,
         if (rep->cpu_list && !test_bit(sample->cpu, rep->cpu_bitmap))
                 return 0;
 
-        if (sort__branch_mode) {
+        if (sort__branch_mode == 1) {
                 if (perf_report__add_branch_hist_entry(tool, &al, sample,
                                                        evsel, machine)) {
                         pr_debug("problem adding lbr entry, skipping event\n");
@@ -239,7 +239,7 @@ static int perf_report__setup_sample_type(struct perf_report *rep)
                         }
         }
 
-        if (sort__branch_mode) {
+        if (sort__branch_mode == 1) {
                 if (!(self->sample_type & PERF_SAMPLE_BRANCH_STACK)) {
                         fprintf(stderr, "selected -b but no branch data."
                                         " Did you call perf record without"
@@ -306,7 +306,7 @@ static int __cmd_report(struct perf_report *rep)
 {
         int ret = -EINVAL;
         u64 nr_samples;
-        struct perf_session *session;
+        struct perf_session *session = rep->session;
         struct perf_evsel *pos;
         struct map *kernel_map;
         struct kmap *kernel_kmap;
@@ -314,13 +314,6 @@ static int __cmd_report(struct perf_report *rep)
 
         signal(SIGINT, sig_handler);
 
-        session = perf_session__new(rep->input_name, O_RDONLY,
-                                    rep->force, false, &rep->tool);
-        if (session == NULL)
-                return -ENOMEM;
-
-        rep->session = session;
-
         if (rep->cpu_list) {
                 ret = perf_session__cpu_bitmap(session, rep->cpu_list,
                                                rep->cpu_bitmap);
@@ -487,9 +480,19 @@ setup:
         return 0;
 }
 
+static int
+parse_branch_mode(const struct option *opt __used, const char *str __used, int unset)
+{
+        sort__branch_mode = !unset;
+        return 0;
+}
+
 int cmd_report(int argc, const char **argv, const char *prefix __used)
 {
+        struct perf_session *session;
         struct stat st;
+        bool has_br_stack = false;
+        int ret = -1;
         char callchain_default_opt[] = "fractal,0.5,callee";
         const char * const report_usage[] = {
                 "perf report [<options>]",
@@ -578,8 +581,8 @@ int cmd_report(int argc, const char **argv, const char *prefix __used)
                    "Specify disassembler style (e.g. -M intel for intel syntax)"),
         OPT_BOOLEAN(0, "show-total-period", &symbol_conf.show_total_period,
                     "Show a column with the sum of periods"),
-        OPT_BOOLEAN('b', "branch-stack", &sort__branch_mode,
-                    "use branch records for histogram filling"),
+        OPT_CALLBACK_NOOPT('b', "branch-stack", &sort__branch_mode, "",
+                    "use branch records for histogram filling", parse_branch_mode),
         OPT_END()
         };
 
@@ -599,8 +602,20 @@ int cmd_report(int argc, const char **argv, const char *prefix __used)
                 else
                         report.input_name = "perf.data";
         }
+        session = perf_session__new(report.input_name, O_RDONLY,
+                                    report.force, false, &report.tool);
+        if (session == NULL)
+                return -ENOMEM;
+
+        report.session = session;
+
+        has_br_stack = perf_header__has_feat(&session->header,
+                                             HEADER_BRANCH_STACK);
 
-        if (sort__branch_mode) {
+        if (sort__branch_mode == -1 && has_br_stack)
+                sort__branch_mode = 1;
+
+        if (sort__branch_mode == 1) {
                 if (use_browser)
                         fprintf(stderr, "Warning: TUI interface not supported"
                                         " in branch mode\n");
@@ -657,13 +672,13 @@ int cmd_report(int argc, const char **argv, const char *prefix __used)
         }
 
         if (symbol__init() < 0)
-                return -1;
+                goto error;
 
         setup_sorting(report_usage, options);
 
         if (parent_pattern != default_parent_pattern) {
                 if (sort_dimension__add("parent") < 0)
-                        return -1;
+                        goto error;
 
                 /*
                  * Only show the parent fields if we explicitly
@@ -685,5 +700,8 @@ int cmd_report(int argc, const char **argv, const char *prefix __used)
         sort_entry__setup_elide(&sort_comm, symbol_conf.comm_list, "comm", stdout);
         sort_entry__setup_elide(&sort_sym, symbol_conf.sym_list, "symbol", stdout);
 
-        return __cmd_report(&report);
+        ret = __cmd_report(&report);
+error:
+        perf_session__delete(session);
+        return ret;
 }
diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index 2739ed10d5e6..88dbcf6f9575 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -8,7 +8,7 @@ const char	default_sort_order[] = "comm,dso,symbol";
 const char      *sort_order = default_sort_order;
 int             sort__need_collapse = 0;
 int             sort__has_parent = 0;
-bool            sort__branch_mode;
+int             sort__branch_mode = -1; /* -1 = means not set */
 
 enum sort_type  sort__first_dimension;
 
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index 7aa72a00bc8e..8505b9bcfa36 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -31,7 +31,7 @@ extern const char *parent_pattern;
 extern const char default_sort_order[];
 extern int sort__need_collapse;
 extern int sort__has_parent;
-extern bool sort__branch_mode;
+extern int sort__branch_mode;
 extern char *field_sep;
 extern struct sort_entry sort_comm;
 extern struct sort_entry sort_dso;