Messages in this thread Patch in this message | | | From | Stephane Eranian <> | Subject | [PATCH 12/13] perf: add support for sampling taken branch to perf record (v3) | Date | Mon, 9 Jan 2012 17:49:20 +0100 |
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From: Roberto Agostino Vitillo <ravitillo@lbl.gov>
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@lbl.gov> Signed-off-by: Stephane Eranian <eranian@google.com> --- 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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