Path: csiph.com!aioe.org!bofh.it!news.nic.it!robomod From: Wang Nan Newsgroups: linux.kernel Subject: [PATCH 20/54] perf core: Set event's default overflow_handler Date: Fri, 05 Feb 2016 15:10:04 +0100 Message-ID: References: X-Original-To: Alexei Starovoitov , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Brendan Gregg X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-Cfilter-Loop: Reflected X-Mirapoint-Virus-Rapid-Raw: score=unknown(0), refid=str=0001.0A020205.56B4ABA3.00DD,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-ID: 1df6681b572edf2ad91b792f9eb37e98 Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 61 Organization: linux.* mail to news gateway X-Original-Cc: Adrian Hunter , Cody P Schafer , "David S. Miller" , He Kuang , =?UTF-8?q?J=C3=A9r=C3=A9mie=20Galarneau?= , Jiri Olsa , Kirill Smelkov , Li Zefan , Masami Hiramatsu , Namhyung Kim , Peter Zijlstra , , Wang Nan , X-Original-Date: Fri, 5 Feb 2016 14:01:45 +0000 X-Original-Message-ID: <1454680939-24963-21-git-send-email-wangnan0@huawei.com> X-Original-References: <1454680939-24963-1-git-send-email-wangnan0@huawei.com> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1327738 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 Cc: He Kuang Cc: Alexei Starovoitov Cc: Arnaldo Carvalho de Melo Cc: Brendan Gregg Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Zefan Li 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 3e6a3ad..77a6475 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; @@ -7869,8 +7866,13 @@ 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