• Wang Nan's avatar
    perf/core: Set event's default ::overflow_handler() · 1879445d
    Wang Nan authored
    Set a default event->overflow_handler in perf_event_alloc() so don't
    need to check event->overflow_handler in __perf_event_overflow().
    Following commits can give a different default overflow_handler.
    
    Initial idea comes from Peter:
    
      http://lkml.kernel.org/r/20130708121557.GA17211@twins.programming.kicks-ass.net
    
    Since the default value of event->overflow_handler is not NULL, existing
    'if (!overflow_handler)' checks need to be changed.
    
    is_default_overflow_handler() is introduced for this.
    
    No extra performance overhead is introduced into the hot path because in the
    original code we still need to read this handler from memory. A conditional
    branch is avoided so actually we remove some instructions.
    Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: <pi3orama@163.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
    Cc: He Kuang <hekuang@huawei.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vince Weaver <vincent.weaver@maine.edu>
    Cc: Zefan Li <lizefan@huawei.com>
    Link: http://lkml.kernel.org/r/1459147292-239310-3-git-send-email-wangnan0@huawei.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    1879445d
hw_breakpoint.c 26.6 KB