perf report: Allow limiting the number of entries to print in callchains

Works by adding a third parameter to the '-g' argument, after the graph
type and minimum percentage, for example:

[root@doppio linux-2.6-tip]# perf report -g fractal,0.5,2

Will show only the first two symbols where at least 0.5% of the samples
took place.

All the other symbols that don't fall outside these constraints will be
put together in the last entry, prefixed with "[...]" and the total
percentage for them.

Suggested-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 15 insertions, 1 deletions

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 5e2f47f88ec6..642a6d8eb5dc 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -343,7 +343,7 @@ static int
 parse_callchain_opt(const struct option *opt __used, const char *arg,
                     int unset)
 {
-        char *tok;
+        char *tok, *tok2;
         char *endptr;
 
         /*
@@ -388,10 +388,13 @@ parse_callchain_opt(const struct option *opt __used, const char *arg,
         if (!tok)
                 goto setup;
 
+        tok2 = strtok(NULL, ",");
         callchain_param.min_percent = strtod(tok, &endptr);
         if (tok == endptr)
                 return -1;
 
+        if (tok2)
+                callchain_param.print_limit = strtod(tok2, &endptr);
 setup:
         if (register_callchain_param(&callchain_param) < 0) {
                 fprintf(stderr, "Can't register callchain params\n");
diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
index 0f4da093cbd8..1cba1f5504e7 100644
--- a/tools/perf/util/callchain.h
+++ b/tools/perf/util/callchain.h
@@ -34,6 +34,7 @@ typedef void (*sort_chain_func_t)(struct rb_root *, struct callchain_node *,
 
 struct callchain_param {
         enum chain_mode         mode;
+        u32                     print_limit;
         double                  min_percent;
         sort_chain_func_t       sort;
 };
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index e0c8a722e11f..0f154a530dfd 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -333,6 +333,7 @@ static size_t __callchain__fprintf_graph(FILE *fp, struct callchain_node *self,
         u64 remaining;
         size_t ret = 0;
         int i;
+        uint entries_printed = 0;
 
         if (callchain_param.mode == CHAIN_GRAPH_REL)
                 new_total = self->children_hit;
@@ -379,6 +380,8 @@ static size_t __callchain__fprintf_graph(FILE *fp, struct callchain_node *self,
                                                   new_depth_mask | (1 << depth),
                                                   left_margin);
                 node = next;
+                if (++entries_printed == callchain_param.print_limit)
+                        break;
         }
 
         if (callchain_param.mode == CHAIN_GRAPH_REL &&
@@ -404,6 +407,7 @@ static size_t callchain__fprintf_graph(FILE *fp, struct callchain_node *self,
         bool printed = false;
         int i = 0;
         int ret = 0;
+        u32 entries_printed = 0;
 
         list_for_each_entry(chain, &self->val, list) {
                 if (!i++ && sort__first_dimension == SORT_SYM)
@@ -424,6 +428,9 @@ static size_t callchain__fprintf_graph(FILE *fp, struct callchain_node *self,
                         ret += fprintf(fp, " %s\n", chain->ms.sym->name);
                 else
                         ret += fprintf(fp, " %p\n", (void *)(long)chain->ip);
+
+                if (++entries_printed == callchain_param.print_limit)
+                        break;
         }
 
         ret += __callchain__fprintf_graph(fp, self, total_samples, 1, 1, left_margin);
@@ -462,6 +469,7 @@ static size_t hist_entry_callchain__fprintf(FILE *fp, struct hist_entry *self,
         struct rb_node *rb_node;
         struct callchain_node *chain;
         size_t ret = 0;
+        u32 entries_printed = 0;
 
         rb_node = rb_first(&self->sorted_chain);
         while (rb_node) {
@@ -484,6 +492,8 @@ static size_t hist_entry_callchain__fprintf(FILE *fp, struct hist_entry *self,
                         break;
                 }
                 ret += fprintf(fp, "\n");
+                if (++entries_printed == callchain_param.print_limit)
+                        break;
                 rb_node = rb_next(rb_node);
         }