4 files changed, 33 insertions, 11 deletions

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index e8219990f8b8..b39f3a1ee7dc 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -162,7 +162,7 @@ static int __cmd_diff(void)
 
         hists__match(&session[0]->hists, &session[1]->hists);
         hists__fprintf(&session[1]->hists, &session[0]->hists,
-                       show_displacement, stdout);
+                       show_displacement, true, 0, 0, stdout);
 out_delete:
         for (i = 0; i < 2; ++i)
                 perf_session__delete(session[i]);
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 3d58334909a5..b125742e5cfd 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -232,7 +232,7 @@ static int perf_evlist__tty_browse_hists(struct perf_evlist *evlist,
                 const char *evname = event_name(pos);
 
                 hists__fprintf_nr_sample_events(hists, evname, stdout);
-                hists__fprintf(hists, NULL, false, stdout);
+                hists__fprintf(hists, NULL, false, true, 0, 0, stdout);
                 fprintf(stdout, "\n\n");
         }
 
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index dd277897ff0b..24cca0a7ffa3 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -710,12 +710,16 @@ int hist_entry__snprintf(struct hist_entry *self, char *s, size_t size,
         return ret;
 }
 
-int hist_entry__fprintf(struct hist_entry *self, struct hists *hists,
+int hist_entry__fprintf(struct hist_entry *he, size_t size, struct hists *hists,
                         struct hists *pair_hists, bool show_displacement,
                         long displacement, FILE *fp, u64 session_total)
 {
         char bf[512];
-        hist_entry__snprintf(self, bf, sizeof(bf), hists, pair_hists,
+
+        if (size == 0 || size > sizeof(bf))
+                size = sizeof(bf);
+
+        hist_entry__snprintf(he, bf, size, hists, pair_hists,
                              show_displacement, displacement,
                              true, session_total);
         return fprintf(fp, "%s\n", bf);
@@ -739,7 +743,8 @@ static size_t hist_entry__fprintf_callchain(struct hist_entry *self,
 }
 
 size_t hists__fprintf(struct hists *hists, struct hists *pair,
-                      bool show_displacement, FILE *fp)
+                      bool show_displacement, bool show_header, int max_rows,
+                      int max_cols, FILE *fp)
 {
         struct sort_entry *se;
         struct rb_node *nd;
@@ -749,9 +754,13 @@ size_t hists__fprintf(struct hists *hists, struct hists *pair,
         unsigned int width;
         const char *sep = symbol_conf.field_sep;
         const char *col_width = symbol_conf.col_width_list_str;
+        int nr_rows = 0;
 
         init_rem_hits();
 
+        if (!show_header)
+                goto print_entries;
+
         fprintf(fp, "# %s", pair ? "Baseline" : "Overhead");
 
         if (symbol_conf.show_nr_samples) {
@@ -814,7 +823,10 @@ size_t hists__fprintf(struct hists *hists, struct hists *pair,
                         width = hists__col_len(hists, se->se_width_idx);
                 fprintf(fp, "  %*s", width, se->se_header);
         }
+
         fprintf(fp, "\n");
+        if (max_rows && ++nr_rows >= max_rows)
+                goto out;
 
         if (sep)
                 goto print_entries;
@@ -841,7 +853,13 @@ size_t hists__fprintf(struct hists *hists, struct hists *pair,
                         fprintf(fp, ".");
         }
 
-        fprintf(fp, "\n#\n");
+        fprintf(fp, "\n");
+        if (max_rows && ++nr_rows >= max_rows)
+                goto out;
+
+        fprintf(fp, "#\n");
+        if (max_rows && ++nr_rows >= max_rows)
+                goto out;
 
 print_entries:
         for (nd = rb_first(&hists->entries); nd; nd = rb_next(nd)) {
@@ -858,19 +876,22 @@ print_entries:
                                 displacement = 0;
                         ++position;
                 }
-                ret += hist_entry__fprintf(h, hists, pair, show_displacement,
+                ret += hist_entry__fprintf(h, max_cols, hists, pair, show_displacement,
                                            displacement, fp, hists->stats.total_period);
 
                 if (symbol_conf.use_callchain)
                         ret += hist_entry__fprintf_callchain(h, hists, fp,
                                                              hists->stats.total_period);
+                if (max_rows && ++nr_rows >= max_rows)
+                        goto out;
+
                 if (h->ms.map == NULL && verbose > 1) {
                         __map_groups__fprintf_maps(&h->thread->mg,
                                                    MAP__FUNCTION, verbose, fp);
                         fprintf(fp, "%.10s end\n", graph_dotted_line);
                 }
         }
-
+out:
         free(rem_sq_bracket);
 
         return ret;
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 3beb97c4d822..861ffc31db96 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -57,9 +57,9 @@ struct hist_entry *__hists__add_entry(struct hists *self,
                                       struct symbol *parent, u64 period);
 extern int64_t hist_entry__cmp(struct hist_entry *, struct hist_entry *);
 extern int64_t hist_entry__collapse(struct hist_entry *, struct hist_entry *);
-int hist_entry__fprintf(struct hist_entry *self, struct hists *hists,
+int hist_entry__fprintf(struct hist_entry *he, size_t size, struct hists *hists,
                         struct hists *pair_hists, bool show_displacement,
-                        long displacement, FILE *fp, u64 total);
+                        long displacement, FILE *fp, u64 session_total);
 int hist_entry__snprintf(struct hist_entry *self, char *bf, size_t size,
                          struct hists *hists, struct hists *pair_hists,
                          bool show_displacement, long displacement,
@@ -73,7 +73,8 @@ void hists__inc_nr_events(struct hists *self, u32 type);
 size_t hists__fprintf_nr_events(struct hists *self, FILE *fp);
 
 size_t hists__fprintf(struct hists *self, struct hists *pair,
-                      bool show_displacement, FILE *fp);
+                      bool show_displacement, bool show_header,
+                      int max_rows, int max_cols, FILE *fp);
 
 int hist_entry__inc_addr_samples(struct hist_entry *self, int evidx, u64 addr);
 int hist_entry__annotate(struct hist_entry *self, size_t privsize);