If an application has an expensive function implemented with a large
tree of calls to helper functions, the default call-graph presentation
will be dominated by the many different call-chains within that
function. By treating the function as a black box, we can collect the
call-chains leading into the function and compactly identify what to
blame for expensive calls.
For example, in this report the callers of garbage_collect() are
scattered across the tree:
$ perf report -d ruby 2>- | grep -m10 ^[^#]*[a-z]
22.03% ruby [.] gc_mark
--- gc_mark
|--59.40%-- mark_keyvalue
| st_foreach
| gc_mark_children
| |--99.75%-- rb_gc_mark
| | rb_vm_mark
| | gc_mark_children
| | gc_marks
| | |--99.00%-- garbage_collect
If we make garbage_collect() a black box, its callers are coalesced:
$ perf report --blackbox garbage_collect -d ruby 2>- | grep -m10 ^[^#]*[a-z]
72.92% ruby [.] garbage_collect
--- garbage_collect
vm_xmalloc
|--47.08%-- ruby_xmalloc
| st_insert2
| rb_hash_aset
| |--98.45%-- features_index_add
| | rb_provide_feature
| | rb_require_safe
| | vm_call_method
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Arnaldo Carvalho de Melo <a...@ghostprotocols.net>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: David Ahern <dsah...@gmail.com>
Signed-off-by: Greg Price <pr...@mit.edu>
---
tools/perf/builtin-report.c | 17 +++++++++++++++--
tools/perf/builtin-top.c | 3 +--
tools/perf/util/map.h | 4 +++-
tools/perf/util/session.c | 29 ++++++++++++++++++-----------
tools/perf/util/session.h | 5 +++++
5 files changed, 42 insertions(+), 16 deletions(-)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index a61725d..3bbda35 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -70,7 +70,7 @@ static int perf_report__add_branch_hist_entry(struct
perf_tool *tool,
if ((sort__has_parent || symbol_conf.use_callchain)
&& sample->callchain) {
err = machine__resolve_callchain(machine, evsel, al->thread,
- sample, &parent);
+ sample, &parent, al);
if (err)
return err;
}
@@ -141,7 +141,7 @@ static int perf_evsel__add_hist_entry(struct perf_evsel
*evsel,
if ((sort__has_parent || symbol_conf.use_callchain) &&
sample->callchain) {
err = machine__resolve_callchain(machine, evsel, al->thread,
- sample, &parent);
+ sample, &parent, al);
if (err)
return err;
}
@@ -607,6 +607,8 @@ int cmd_report(int argc, const char **argv, const char
*prefix __maybe_unused)
"Default: fractal,0.5,callee", &parse_callchain_opt,
callchain_default_opt),
OPT_BOOLEAN('G', "inverted", &report.inverted_callchain,
"alias for inverted call graph"),
+ OPT_STRING(0, "blackbox", &blackbox_pattern, "regex",
+ "functions to treat as black boxes in call graphs,
collapsing callees"),
OPT_STRING('d', "dsos", &symbol_conf.dso_list_str, "dso[,dso...]",
"only consider symbols in these dsos"),
OPT_STRING('c', "comms", &symbol_conf.comm_list_str, "comm[,comm...]",
@@ -687,6 +689,17 @@ int cmd_report(int argc, const char **argv, const char
*prefix __maybe_unused)
}
+ if (blackbox_pattern) {
+ int err = regcomp(&blackbox_regex, blackbox_pattern,
REG_EXTENDED);
+ if (err) {
+ char buf[BUFSIZ];
+ regerror(err, &blackbox_regex, buf, sizeof(buf));
+ pr_err("Invalid blackbox regex: %s\n%s",
blackbox_pattern, buf);
+ goto error;
+ }
+ have_blackbox = 1;
+ }
+
if (strcmp(report.input_name, "-") != 0)
setup_browser(true);
else {
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ff6db80..ee969b5 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -786,8 +786,7 @@ static void perf_event__process_sample(struct perf_tool
*tool,
sample->callchain) {
err = machine__resolve_callchain(machine, evsel,
al.thread, sample,
- &parent);
-
+ &parent, NULL);
if (err)
return;
}
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index d2250fc..6d1b8e1 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -23,6 +23,7 @@ struct ref_reloc_sym;
struct map_groups;
struct machine;
struct perf_evsel;
+struct addr_location;
struct map {
union {
@@ -163,7 +164,8 @@ int machine__resolve_callchain(struct machine *machine,
struct perf_evsel *evsel,
struct thread *thread,
struct perf_sample *sample,
- struct symbol **parent);
+ struct symbol **parent,
+ struct addr_location *root_al);
int maps__set_kallsyms_ref_reloc_sym(struct map **maps, const char
*symbol_name,
u64 addr);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 8cdd232..9a8798c 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -19,6 +19,10 @@
#include "unwind.h"
#include "vdso.h"
+regex_t blackbox_regex;
+const char *blackbox_pattern;
+int have_blackbox = 0;
+
static int perf_session__open(struct perf_session *self, bool force)
{
struct stat input_stat;
@@ -226,11 +230,10 @@ void machine__remove_thread(struct machine *self, struct
thread *th)
list_add_tail(&th->node, &self->dead_threads);
}
-static bool symbol__match_parent_regex(struct symbol *sym)
+static bool symbol__match_regex(struct symbol *sym, regex_t *regex)
{
- if (sym->name && !regexec(&parent_regex, sym->name, 0, NULL, 0))
+ if (sym->name && !regexec(regex, sym->name, 0, NULL, 0))
return 1;
-
return 0;
}
@@ -295,8 +298,8 @@ struct branch_info *machine__resolve_bstack(struct machine
*self,
static int machine__resolve_callchain_sample(struct machine *machine,
struct thread *thread,
struct ip_callchain *chain,
- struct symbol **parent)
-
+ struct symbol **parent,
+ struct addr_location *root_al)
{
u8 cpumode = PERF_RECORD_MISC_USER;
unsigned int i;
@@ -347,8 +350,13 @@ static int machine__resolve_callchain_sample(struct
machine *machine,
MAP__FUNCTION, ip, &al, NULL);
if (al.sym != NULL) {
if (sort__has_parent && !*parent &&
- symbol__match_parent_regex(al.sym))
+ symbol__match_regex(al.sym, &parent_regex))
*parent = al.sym;
+ else if (have_blackbox && root_al &&
+ symbol__match_regex(al.sym, &blackbox_regex)) {
+ *root_al = al;
+ callchain_cursor_reset(&callchain_cursor);
+ }
if (!symbol_conf.use_callchain)
break;
}
@@ -373,15 +381,15 @@ int machine__resolve_callchain(struct machine *machine,
struct perf_evsel *evsel,
struct thread *thread,
struct perf_sample *sample,
- struct symbol **parent)
-
+ struct symbol **parent,
+ struct addr_location *root_al)
{
int ret;
callchain_cursor_reset(&callchain_cursor);
ret = machine__resolve_callchain_sample(machine, thread,
- sample->callchain, parent);
+ sample->callchain, parent,
root_al);
if (ret)
return ret;
@@ -1603,9 +1611,8 @@ void perf_evsel__print_ip(struct perf_evsel *evsel, union
perf_event *event,
if (symbol_conf.use_callchain && sample->callchain) {
-
if (machine__resolve_callchain(machine, evsel, al.thread,
- sample, NULL) != 0) {
+ sample, NULL, NULL) != 0) {
if (verbose)
error("Failed to resolve callchain.
Skipping\n");
return;
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 0eae00a..6db3e55 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -1,6 +1,7 @@
#ifndef __PERF_SESSION_H
#define __PERF_SESSION_H
+#include <regex.h>
#include "hist.h"
#include "event.h"
#include "header.h"
@@ -9,6 +10,10 @@
#include <linux/rbtree.h>
#include <linux/perf_event.h>
+extern regex_t blackbox_regex;
+extern const char *blackbox_pattern;
+extern int have_blackbox;
+
struct sample_queue;
struct ip_callchain;
struct thread;
--
1.7.11.3
--
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