Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756698AbcCaJ1h (ORCPT ); Thu, 31 Mar 2016 05:27:37 -0400 Received: from terminus.zytor.com ([198.137.202.10]:38228 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756516AbcCaJ1b (ORCPT ); Thu, 31 Mar 2016 05:27:31 -0400 Date: Thu, 31 Mar 2016 02:26:29 -0700 From: tip-bot for Wang Nan Message-ID: Cc: peterz@infradead.org, wangnan0@huawei.com, mingo@kernel.org, hekuang@huawei.com, jolsa@redhat.com, alexander.shishkin@linux.intel.com, tglx@linutronix.de, masami.hiramatsu.pt@hitachi.com, hpa@zytor.com, namhyung@kernel.org, brendan.d.gregg@gmail.com, jolsa@kernel.org, ast@kernel.org, pi3orama@163.com, acme@redhat.com, linux-kernel@vger.kernel.org, lizefan@huawei.com, torvalds@linux-foundation.org, vincent.weaver@maine.edu, eranian@google.com Reply-To: namhyung@kernel.org, hpa@zytor.com, brendan.d.gregg@gmail.com, mingo@kernel.org, wangnan0@huawei.com, peterz@infradead.org, hekuang@huawei.com, tglx@linutronix.de, jolsa@redhat.com, alexander.shishkin@linux.intel.com, masami.hiramatsu.pt@hitachi.com, lizefan@huawei.com, torvalds@linux-foundation.org, vincent.weaver@maine.edu, eranian@google.com, jolsa@kernel.org, ast@kernel.org, linux-kernel@vger.kernel.org, pi3orama@163.com, acme@redhat.com In-Reply-To: <1459147292-239310-3-git-send-email-wangnan0@huawei.com> References: <1459147292-239310-3-git-send-email-wangnan0@huawei.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf/core: Set event's default ::overflow_handler() Git-Commit-ID: 1879445dfa7bbd6fe21b09c5cc72f4934798afed X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5331 Lines: 146 Commit-ID: 1879445dfa7bbd6fe21b09c5cc72f4934798afed Gitweb: http://git.kernel.org/tip/1879445dfa7bbd6fe21b09c5cc72f4934798afed Author: Wang Nan AuthorDate: Mon, 28 Mar 2016 06:41:30 +0000 Committer: Ingo Molnar CommitDate: Thu, 31 Mar 2016 10:30:47 +0200 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 --- 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 51386e8..8c3b35f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6628,10 +6628,7 @@ 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; @@ -8152,8 +8149,13 @@ 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);