lkml.org 
[lkml]   [2012]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v6 12/18] perf: add support for sampling taken branch to perf record
    Date
    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
    - hv: only when the branch target is in the hypervisor

    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 | 25 ++++++++++
    tools/perf/builtin-record.c | 74 ++++++++++++++++++++++++++++++
    tools/perf/perf.h | 1 +
    tools/perf/util/evsel.c | 4 ++
    4 files changed, 104 insertions(+), 0 deletions(-)

    diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
    index ff9a66e..288d429 100644
    --- a/tools/perf/Documentation/perf-record.txt
    +++ b/tools/perf/Documentation/perf-record.txt
    @@ -152,6 +152,31 @@ 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 interest, and the executed code.
    +It is possible to select the types of branches captured 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
    + - hv: only when the target is at the hypervisor level
    +
    ++
    +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 are applied to the
    +branch filter. Both kernel (k) and hypervisor (hv) privilege levels are subject to
    +permissions. 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.
    +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 f8d9a54..9f07418 100644
    --- a/tools/perf/builtin-record.c
    +++ b/tools/perf/builtin-record.c
    @@ -627,6 +627,77 @@ 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("hv", PERF_SAMPLE_BRANCH_HV),
    + 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 |\
    + PERF_SAMPLE_BRANCH_HV)
    +
    + 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>]",
    @@ -719,6 +790,9 @@ const struct option record_options[] = {
    "monitor event in cgroup name only",
    parse_cgroups),
    OPT_STRING('u', "uid", &record.uid_str, "user", "user to profile"),
    + 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 8b4d25d..7f8fbab 100644
    --- a/tools/perf/perf.h
    +++ b/tools/perf/perf.h
    @@ -222,6 +222,7 @@ 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 f310aa5..9f66df6 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;
    --
    1.7.4.1


    \
     
     \ /
      Last update: 2012-02-09 23:27    [W:0.042 / U:32.204 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site