Messages in this thread Patch in this message |  | | From | Wang Nan <> | Subject | [PATCH 21/55] perf core: Set event's default overflow_handler | Date | Fri, 19 Feb 2016 11:44:09 +0000 |
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Set a default event->overflow_handler in perf_event_alloc() so don't need checking event->overflow_handler in __perf_event_overflow(). Following commits can give a different default overflow_handler.
No extra performance introduced into hot path because in the original code we still need reading this handler from memory. A conditional branch is avoided so actually we remove some instructions.
Initial idea comes from Peter at [1].
[1] http://lkml.kernel.org/r/20130708121557.GA17211@twins.programming.kicks-ass.net
Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: He Kuang <hekuang@huawei.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com --- kernel/events/core.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index a7075ae..ae34061 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6392,10 +6392,7 @@ static int __perf_event_overflow(struct perf_event *event, irq_work_queue(&event->pending); } - if (event->overflow_handler) - event->overflow_handler(event, data, regs); - else - perf_event_output(event, data, regs); + event->overflow_handler(event, data, regs); if (*perf_event_fasync(event) && event->pending_kill) { event->pending_wakeup = 1; @@ -7868,8 +7865,13 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, context = parent_event->overflow_handler_context; } - event->overflow_handler = overflow_handler; - event->overflow_handler_context = context; + if (overflow_handler) { + event->overflow_handler = overflow_handler; + event->overflow_handler_context = context; + } else { + event->overflow_handler = perf_event_output; + event->overflow_handler_context = NULL; + } perf_event__state_init(event); -- 1.8.3.4
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