Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932775Ab3GQQo6 (ORCPT ); Wed, 17 Jul 2013 12:44:58 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:58255 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932701Ab3GQQoy (ORCPT ); Wed, 17 Jul 2013 12:44:54 -0400 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Steven Rostedt , "Paul E. McKenney" , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Borislav Petkov , Li Zhong , Mike Galbraith , Kevin Hilman Subject: [PATCH 08/18] context_tracking: Ground setup for static key use Date: Wed, 17 Jul 2013 18:44:21 +0200 Message-Id: <1374079471-3129-9-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1374079471-3129-1-git-send-email-fweisbec@gmail.com> References: <1374079471-3129-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2826 Lines: 93 Prepare for using a static key in the context tracking subsystem. This will help optimizing the off case on its many users: * user_enter, user_exit, exception_enter, exception_exit, guest_enter, guest_exit, vtime_*() Signed-off-by: Frederic Weisbecker Cc: Steven Rostedt Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Li Zhong Cc: Mike Galbraith Cc: Kevin Hilman --- include/linux/context_tracking.h | 2 ++ kernel/context_tracking.c | 26 ++++++++++++++++++++------ 2 files changed, 22 insertions(+), 6 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 2c2b73aa..0007ab4 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -4,6 +4,7 @@ #include #include #include +#include #include struct context_tracking { @@ -22,6 +23,7 @@ struct context_tracking { #ifdef CONFIG_CONTEXT_TRACKING +extern struct static_key context_tracking_enabled; DECLARE_PER_CPU(struct context_tracking, context_tracking); static inline bool context_tracking_in_user(void) diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 72bcb25..f07505c 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -20,15 +20,16 @@ #include #include -DEFINE_PER_CPU(struct context_tracking, context_tracking) = { -#ifdef CONFIG_CONTEXT_TRACKING_FORCE - .active = true, -#endif -}; +struct static_key context_tracking_enabled = STATIC_KEY_INIT_FALSE; + +DEFINE_PER_CPU(struct context_tracking, context_tracking); void context_tracking_cpu_set(int cpu) { - per_cpu(context_tracking.active, cpu) = true; + if (!per_cpu(context_tracking.active, cpu)) { + per_cpu(context_tracking.active, cpu) = true; + static_key_slow_inc(&context_tracking_enabled); + } } /** @@ -202,3 +203,16 @@ void context_tracking_task_switch(struct task_struct *prev, clear_tsk_thread_flag(prev, TIF_NOHZ); set_tsk_thread_flag(next, TIF_NOHZ); } + +#ifdef CONFIG_CONTEXT_TRACKING_FORCE +static int __init context_tracking_init(void) +{ + int cpu; + + for_each_possible_cpu(cpu) + context_tracking_cpu_set(cpu); + + return 0; +} +early_initcall(context_tracking_init); +#endif -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/