From 1879445dfa7bbd6fe21b09c5cc72f4934798afed Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 28 Mar 2016 06:41:30 +0000 Subject: perf/core: Set event's default ::overflow_handler() 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: Wang Nan Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Alexander Shishkin Cc: Alexei Starovoitov Cc: Arnaldo Carvalho de Melo Cc: Brendan Gregg Cc: He Kuang Cc: Jiri Olsa Cc: Jiri Olsa Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: Zefan Li Link: http://lkml.kernel.org/r/1459147292-239310-3-git-send-email-wangnan0@huawei.com Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 15588d4c581d..4065ca2d7149 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -838,6 +838,12 @@ extern void perf_event_output(struct perf_event *event, struct perf_sample_data *data, struct pt_regs *regs); +static inline bool +is_default_overflow_handler(struct perf_event *event) +{ + return (event->overflow_handler == perf_event_output); +} + extern void perf_event_header__init_id(struct perf_event_header *header, struct perf_sample_data *data, -- cgit v1.2.3