Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754803AbcC1GnF (ORCPT ); Mon, 28 Mar 2016 02:43:05 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:31672 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753616AbcC1Gmd (ORCPT ); Mon, 28 Mar 2016 02:42:33 -0400 From: Wang Nan To: Alexei Starovoitov , Arnaldo Carvalho de Melo , Peter Zijlstra CC: , Brendan Gregg , He Kuang , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , , Wang Nan , Zefan Li Subject: [PATCH 2/4] perf core: Set event's default overflow_handler Date: Mon, 28 Mar 2016 06:41:30 +0000 Message-ID: <1459147292-239310-3-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1459147292-239310-1-git-send-email-wangnan0@huawei.com> References: <1459147292-239310-1-git-send-email-wangnan0@huawei.com> 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=0001.0A020203.56F8D242.003D,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: adbffc44051120f701d3b02460d935df Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4497 Lines: 129 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 at [1] Since default value of event->overflow_handler is not null, existing 'if (!overflow_handler)' need to be changed. is_default_overflow_handler() is introduced for this. 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. [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 --- arch/arm/kernel/hw_breakpoint.c | 4 ++-- arch/arm64/kernel/hw_breakpoint.c | 4 ++-- include/linux/perf_event.h | 6 ++++++ kernel/events/core.c | 14 ++++++++------ 4 files changed, 18 insertions(+), 10 deletions(-) diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index 6284779..b8df458 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -631,7 +631,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) info->address &= ~alignment_mask; info->ctrl.len <<= offset; - if (!bp->overflow_handler) { + if (is_default_overflow_handler(bp)) { /* * Mismatch breakpoints are required for single-stepping * breakpoints. @@ -754,7 +754,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr, * mismatch breakpoint so we can single-step over the * watchpoint trigger. */ - if (!wp->overflow_handler) + if (is_default_overflow_handler(wp)) enable_single_step(wp, instruction_pointer(regs)); unlock: diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index b45c95d..4ef5373 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -616,7 +616,7 @@ static int breakpoint_handler(unsigned long unused, unsigned int esr, perf_bp_event(bp, regs); /* Do we need to handle the stepping? */ - if (!bp->overflow_handler) + if (is_default_overflow_handler(bp)) step = 1; unlock: rcu_read_unlock(); @@ -712,7 +712,7 @@ static int watchpoint_handler(unsigned long addr, unsigned int esr, perf_bp_event(wp, regs); /* Do we need to handle the stepping? */ - if (!wp->overflow_handler) + if (is_default_overflow_handler(wp)) step = 1; unlock: diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 15588d4..4065ca2 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, diff --git a/kernel/events/core.c b/kernel/events/core.c index cb47da3..3bd4b2b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6502,10 +6502,7 @@ 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; @@ -8017,8 +8014,13 @@ 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