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    Subject[tip:perf/core] perf callchain: Use global caching provided by libunwind
    Commit-ID:  380b5143ab76de71572c7a30e68c8e22b94bee52
    Gitweb: http://git.kernel.org/tip/380b5143ab76de71572c7a30e68c8e22b94bee52
    Author: Namhyung Kim <namhyung@kernel.org>
    AuthorDate: Mon, 6 Oct 2014 09:46:01 +0900
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Wed, 29 Oct 2014 10:25:22 -0200

    perf callchain: Use global caching provided by libunwind

    The libunwind provides two caching policy which are global and
    per-thread. As perf unwinds callchains in a single thread, it'd
    sufficient to use global caching.

    This speeds up my perf report from 14s to 7s on a ~260MB data file.
    Although the output sometimes contains a slight difference (~0.01% in
    terms of number of lines printed) on callchains which were not resolved.

    Signed-off-by: Namhyung Kim <namhyung@kernel.org>
    Acked-by: Jean Pihet <jean.pihet@linaro.org>
    Cc: Arun Sharma <asharma@fb.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Jean Pihet <jean.pihet@linaro.org>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Namhyung Kim <namhyung.kim@lge.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/1412556363-26229-4-git-send-email-namhyung@kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/thread.c | 3 +++
    tools/perf/util/unwind-libunwind.c | 12 ++++++++++++
    tools/perf/util/unwind.h | 3 +++
    3 files changed, 18 insertions(+)

    diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
    index 2b7b2d9..c414117 100644
    --- a/tools/perf/util/thread.c
    +++ b/tools/perf/util/thread.c
    @@ -117,6 +117,9 @@ int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
    if (!new)
    return -ENOMEM;
    list_add(&new->list, &thread->comm_list);
    +
    + if (exec)
    + unwind__flush_access(thread);
    }

    thread->comm_set = true;
    diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
    index e060386..4d45c0d 100644
    --- a/tools/perf/util/unwind-libunwind.c
    +++ b/tools/perf/util/unwind-libunwind.c
    @@ -539,11 +539,23 @@ int unwind__prepare_access(struct thread *thread)
    return -ENOMEM;
    }

    + unw_set_caching_policy(addr_space, UNW_CACHE_GLOBAL);
    thread__set_priv(thread, addr_space);

    return 0;
    }

    +void unwind__flush_access(struct thread *thread)
    +{
    + unw_addr_space_t addr_space;
    +
    + if (callchain_param.record_mode != CALLCHAIN_DWARF)
    + return;
    +
    + addr_space = thread__priv(thread);
    + unw_flush_cache(addr_space, 0, 0);
    +}
    +
    void unwind__finish_access(struct thread *thread)
    {
    unw_addr_space_t addr_space;
    diff --git a/tools/perf/util/unwind.h b/tools/perf/util/unwind.h
    index c17c485..f50b737 100644
    --- a/tools/perf/util/unwind.h
    +++ b/tools/perf/util/unwind.h
    @@ -23,6 +23,7 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
    #ifdef HAVE_LIBUNWIND_SUPPORT
    int libunwind__arch_reg_id(int regnum);
    int unwind__prepare_access(struct thread *thread);
    +void unwind__flush_access(struct thread *thread);
    void unwind__finish_access(struct thread *thread);
    #else
    static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
    @@ -30,6 +31,7 @@ static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
    return 0;
    }

    +static inline void unwind__flush_access(struct thread *thread __maybe_unused) {}
    static inline void unwind__finish_access(struct thread *thread __maybe_unused) {}
    #endif
    #else
    @@ -49,6 +51,7 @@ static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
    return 0;
    }

    +static inline void unwind__flush_access(struct thread *thread __maybe_unused) {}
    static inline void unwind__finish_access(struct thread *thread __maybe_unused) {}
    #endif /* HAVE_DWARF_UNWIND_SUPPORT */
    #endif /* __UNWIND_H */

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