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    Subject[tip:perf/core] perf evlist: Drop redundant evsel->overwrite indicator
    Commit-ID:  32a951b4fd6bbe60ef5d65930b1712321e241b27
    Gitweb: http://git.kernel.org/tip/32a951b4fd6bbe60ef5d65930b1712321e241b27
    Author: Arnaldo Carvalho de Melo <acme@redhat.com>
    AuthorDate: Thu, 14 Jul 2016 08:34:33 +0000
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Fri, 15 Jul 2016 13:38:06 -0300

    perf evlist: Drop redundant evsel->overwrite indicator

    evsel->overwrite indicator means an event should be put into
    overwritable ring buffer. In current implementation, it equals to
    evsel->attr.write_backward. To reduce compliexity, remove
    evsel->overwrite, use evsel->attr.write_backward instead.

    In addition, in __perf_evsel__open(), if kernel doesn't support
    write_backward and user explicitly set it in evsel, don't fallback
    like other missing feature, since it is meaningless to fall back to
    a forward ring buffer in this case: we are unable to stably read
    from an forward overwritable ring buffer.

    Cc: He Kuang <hekuang@huawei.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Nilay Vaish <nilayvaish@gmail.com>
    Cc: Wang Nan <wangnan0@huawei.com>
    Cc: Zefan Li <lizefan@huawei.com>
    Cc: pi3orama@163.com
    Link: http://lkml.kernel.org/r/1468485287-33422-2-git-send-email-wangnan0@huawei.com
    Signed-off-by: Wang Nan <wangnan0@huawei.com>
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/tests/backward-ring-buffer.c | 1 +
    tools/perf/util/evlist.c | 4 ++--
    tools/perf/util/evsel.c | 12 +++++-------
    tools/perf/util/evsel.h | 1 -
    4 files changed, 8 insertions(+), 10 deletions(-)

    diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
    index f20ea4c..5cee387 100644
    --- a/tools/perf/tests/backward-ring-buffer.c
    +++ b/tools/perf/tests/backward-ring-buffer.c
    @@ -101,6 +101,7 @@ int test__backward_ring_buffer(int subtest __maybe_unused)
    return TEST_FAIL;
    }

    + evlist->backward = true;
    err = perf_evlist__create_maps(evlist, &opts.target);
    if (err < 0) {
    pr_debug("Not enough memory to create thread/cpu maps\n");
    diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
    index 862e69c..6803f5c 100644
    --- a/tools/perf/util/evlist.c
    +++ b/tools/perf/util/evlist.c
    @@ -1003,7 +1003,7 @@ static bool
    perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
    struct perf_evsel *evsel)
    {
    - if (evsel->overwrite)
    + if (evsel->attr.write_backward)
    return false;
    return true;
    }
    @@ -1018,7 +1018,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
    evlist__for_each_entry(evlist, evsel) {
    int fd;

    - if (evsel->overwrite != (evlist->overwrite && evlist->backward))
    + if (!!evsel->attr.write_backward != (evlist->overwrite && evlist->backward))
    continue;

    if (evsel->system_wide && thread)
    diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
    index ba0f59f..9ac2f92 100644
    --- a/tools/perf/util/evsel.c
    +++ b/tools/perf/util/evsel.c
    @@ -1377,6 +1377,9 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
    int pid = -1, err;
    enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;

    + if (perf_missing_features.write_backward && evsel->attr.write_backward)
    + return -EINVAL;
    +
    if (evsel->system_wide)
    nthreads = 1;
    else
    @@ -1407,11 +1410,6 @@ fallback_missing_features:
    if (perf_missing_features.lbr_flags)
    evsel->attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
    PERF_SAMPLE_BRANCH_NO_CYCLES);
    - if (perf_missing_features.write_backward) {
    - if (evsel->overwrite)
    - return -EINVAL;
    - evsel->attr.write_backward = false;
    - }
    retry_sample_id:
    if (perf_missing_features.sample_id_all)
    evsel->attr.sample_id_all = 0;
    @@ -1513,7 +1511,7 @@ try_fallback:
    */
    if (!perf_missing_features.write_backward && evsel->attr.write_backward) {
    perf_missing_features.write_backward = true;
    - goto fallback_missing_features;
    + goto out_close;
    } else if (!perf_missing_features.clockid_wrong && evsel->attr.use_clockid) {
    perf_missing_features.clockid_wrong = true;
    goto fallback_missing_features;
    @@ -2422,7 +2420,7 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
    "We found oprofile daemon running, please stop it and try again.");
    break;
    case EINVAL:
    - if (evsel->overwrite && perf_missing_features.write_backward)
    + if (evsel->attr.write_backward && perf_missing_features.write_backward)
    return scnprintf(msg, size, "Reading from overwrite event is not supported by this kernel.");
    if (perf_missing_features.clockid)
    return scnprintf(msg, size, "clockid feature not supported.");
    diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
    index d73391e..e60cbfc 100644
    --- a/tools/perf/util/evsel.h
    +++ b/tools/perf/util/evsel.h
    @@ -114,7 +114,6 @@ struct perf_evsel {
    bool tracking;
    bool per_pkg;
    bool precise_max;
    - bool overwrite;
    /* parse modifier helper */
    int exclude_GH;
    int nr_members;
    \
     
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