Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753405Ab3HAAi0 (ORCPT ); Wed, 31 Jul 2013 20:38:26 -0400 Received: from mail-wi0-f182.google.com ([209.85.212.182]:64081 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752354Ab3HAAcC (ORCPT ); Wed, 31 Jul 2013 20:32:02 -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 10/23] context_tracking: Optimize context switch off case with static keys Date: Thu, 1 Aug 2013 02:31:27 +0200 Message-Id: <1375317100-20651-11-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1375317100-20651-1-git-send-email-fweisbec@gmail.com> References: <1375317100-20651-1-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: 3005 Lines: 86 No need for syscall slowpath if no CPU is full dynticks, rather nop this in this case. 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 | 11 +++++++++-- kernel/context_tracking.c | 6 +++--- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 03a32b0..66a8397 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -40,6 +40,8 @@ extern void context_tracking_cpu_set(int cpu); extern void context_tracking_user_enter(void); extern void context_tracking_user_exit(void); +extern void __context_tracking_task_switch(struct task_struct *prev, + struct task_struct *next); static inline void user_enter(void) { @@ -74,8 +76,12 @@ static inline void exception_exit(enum ctx_state prev_ctx) } } -extern void context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next); +static inline void context_tracking_task_switch(struct task_struct *prev, + struct task_struct *next) +{ + if (static_key_false(&context_tracking_enabled)) + __context_tracking_task_switch(prev, next); +} #else static inline bool context_tracking_in_user(void) { return false; } static inline void user_enter(void) { } @@ -104,6 +110,7 @@ static inline void guest_exit(void) else current->flags &= ~PF_VCPU; } + #else static inline void guest_enter(void) { diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 5afa36b..ef21e4f 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -166,7 +166,7 @@ void context_tracking_user_exit(void) } /** - * context_tracking_task_switch - context switch the syscall callbacks + * __context_tracking_task_switch - context switch the syscall callbacks * @prev: the task that is being switched out * @next: the task that is being switched in * @@ -178,8 +178,8 @@ void context_tracking_user_exit(void) * migrate to some CPU that doesn't do the context tracking. As such the TIF * flag may not be desired there. */ -void context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next) +void __context_tracking_task_switch(struct task_struct *prev, + struct task_struct *next) { clear_tsk_thread_flag(prev, TIF_NOHZ); set_tsk_thread_flag(next, TIF_NOHZ); -- 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/