[PATCH 12/13] perf: add support for sampling taken branch to perf record (v3)
From: Stephane Eranian
Date: Mon Jan 09 2012 - 11:51:31 EST
From: Roberto Agostino Vitillo <ravitillo@xxxxxxx>
This patch adds a new option to enable taken branch stack
sampling, i.e., leverage the PERF_SAMPLE_BRANCH_STACK feature
of perf_events.
There is a new option to active this mode: -b.
It is possible to pass a set of filters to select the type of
branches to sample.
The following filters are available:
- any : any type of branches
- any_call : any function call or system call
- any_ret : any function return or system call return
- any_ind : any indirect branch
- u: only when the branch target is at the user level
- k: only when the branch target is in the kernel
Filters can be combined by passing a comma separated list
to the option:
$ perf record -b any_call,u -e cycles:u branchy
Signed-off-by: Roberto Agostino Vitillo <ravitillo@xxxxxxx>
Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
---
tools/perf/Documentation/perf-record.txt | 18 ++++++++
tools/perf/builtin-record.c | 69 ++++++++++++++++++++++++++++++
tools/perf/perf.h | 1 +
tools/perf/util/evsel.c | 4 ++
4 files changed, 92 insertions(+), 0 deletions(-)
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 2937f7e..69068d0 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -148,6 +148,24 @@ an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must ha
corresponding events, i.e., they always refer to events defined earlier on the command
line.
+-b::
+--branch-stack::
+Enable taken branch stack sampling. Each sample captures a series of consecutive
+taken branches. The number of branches captured with each sample depends on the
+underlying hardware, the type of branches of interested and the executed code.
+It is possible to filter the types of branches by enabling filters. The
+following filters are defined: any (any type of branches), any_call (any function
+call or system call), any_ret (any function return or system call return), any_ind
+(any indirect branch), u (only when the branch target is at the user level), k (only when
+the branch target is in the kernel). At least one of any, any_call, any_ret, any_ind
+must be provided. The privilege levels may be ommitted, in which case, the privilege
+levels of the associated event is applied to the branch filter. When sampling on multiple
+events, branch stack sampling is enabled for all the sampling events. The sampled branch
+type is the same for all events. The privilege levels are adjusted based on those of
+the associated event unless specified explicitly with this option. Note that taken
+branch sampling may not be available on all processors. The various filters must
+be specified as a comma separated list: -b any_ret,u,k
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0abfb18..df79d23 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -636,6 +636,72 @@ static int __cmd_record(struct perf_record *rec, int argc, const char **argv)
return err;
}
+#define BRANCH_OPT(n, m) \
+ { .name = n, .mode = (m) }
+
+#define BRANCH_END { .name = NULL }
+
+struct branch_mode {
+ const char *name;
+ int mode;
+};
+
+static const struct branch_mode branch_modes[]={
+ BRANCH_OPT("u", PERF_SAMPLE_BRANCH_USER),
+ BRANCH_OPT("k", PERF_SAMPLE_BRANCH_KERNEL),
+ BRANCH_OPT("any", PERF_SAMPLE_BRANCH_ANY),
+ BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
+ BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
+ BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
+ BRANCH_END
+};
+
+static int
+parse_branch_stack(const struct option *opt, const char *str, int unset __used)
+{
+#define ONLY_PLM (PERF_SAMPLE_BRANCH_USER|PERF_SAMPLE_BRANCH_KERNEL)
+ uint64_t *mode = (uint64_t *)opt->value;
+ const struct branch_mode *br;
+ char *s, *os, *p;
+ int ret = -1;
+
+ *mode = 0;
+
+ /* because str is read-only */
+ s = os = strdup(str);
+ if (!s)
+ return -1;
+
+ for (;;) {
+ p = strchr(s, ',');
+ if (p)
+ *p = '\0';
+
+ for (br = branch_modes; br->name; br++) {
+ if (!strcasecmp(s, br->name))
+ break;
+ }
+ if (!br->name)
+ goto error;
+
+ *mode |= br->mode;
+
+ if (!p)
+ break;
+
+ s = p + 1;
+ }
+ ret = 0;
+
+ if ((*mode & ~ONLY_PLM) == 0) {
+ error("need at least one branch type with -b\n");
+ ret = -1;
+ }
+error:
+ free(os);
+ return ret;
+}
+
static const char * const record_usage[] = {
"perf record [<options>] [<command>]",
"perf record [<options>] -- <command> [<options>]",
@@ -727,6 +793,9 @@ const struct option record_options[] = {
OPT_CALLBACK('G', "cgroup", &record.evlist, "name",
"monitor event in cgroup name only",
parse_cgroups),
+ OPT_CALLBACK('b', "branch stack", &record.opts.branch_stack, "branch mode mask",
+ "branch stack sampling modes",
+ parse_branch_stack),
OPT_END()
};
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 513617c..dec5b4c 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -221,6 +221,7 @@ struct perf_record_opts {
unsigned int freq;
unsigned int mmap_pages;
unsigned int user_freq;
+ int branch_stack;
u64 default_interval;
u64 user_interval;
const char *cpu_list;
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 472fc8c..a65a53c 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -126,6 +126,10 @@ void perf_evsel__config(struct perf_evsel *evsel, struct perf_record_opts *opts)
attr->watermark = 0;
attr->wakeup_events = 1;
}
+ if (opts->branch_stack) {
+ attr->sample_type |= PERF_SAMPLE_BRANCH_STACK;
+ attr->branch_sample_type = opts->branch_stack;
+ }
attr->mmap = track;
attr->comm = track;
--
1.7.1
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