From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754896Ab3I1I3p (ORCPT ); Sat, 28 Sep 2013 04:29:45 -0400 Received: from terminus.zytor.com ([198.137.202.10]:44500 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752659Ab3I1I3N (ORCPT ); Sat, 28 Sep 2013 04:29:13 -0400 Date: Sat, 28 Sep 2013 01:28:30 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, ying.huang@intel.com, yuanhan.liu@linux.intel.com, tglx@linutronix.de, fengguang.wu@intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, ying.huang@intel.com, yuanhan.liu@linux.intel.com, tglx@linutronix.de, fengguang.wu@intel.com In-Reply-To: <20130927153003.GF15690@laptop.programming.kicks-ass.net> References: <20130927153003.GF15690@laptop.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Revert need_resched() to look at TIF_NEED_RESCHED Git-Commit-ID: 75f93fed50c2abadbab6ef546b265f51ca975b27 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 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Sat, 28 Sep 2013 01:28:37 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 75f93fed50c2abadbab6ef546b265f51ca975b27 Gitweb: http://git.kernel.org/tip/75f93fed50c2abadbab6ef546b265f51ca975b27 Author: Peter Zijlstra AuthorDate: Fri, 27 Sep 2013 17:30:03 +0200 Committer: Ingo Molnar CommitDate: Sat, 28 Sep 2013 10:04:47 +0200 sched: Revert need_resched() to look at TIF_NEED_RESCHED Yuanhan reported a serious throughput regression in his pigz benchmark. Using the ftrace patch I found that several idle paths need more TLC before we can switch the generic need_resched() over to preempt_need_resched. The preemption paths benefit most from preempt_need_resched and do indeed use it; all other need_resched() users don't really care that much so reverting need_resched() back to tif_need_resched() is the simple and safe solution. Reported-by: Yuanhan Liu Signed-off-by: Peter Zijlstra Cc: Fengguang Wu Cc: Huang Ying Cc: lkp@linux.intel.com Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20130927153003.GF15690@laptop.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- arch/x86/include/asm/preempt.h | 8 -------- include/asm-generic/preempt.h | 8 -------- include/linux/sched.h | 5 +++++ 3 files changed, 5 insertions(+), 16 deletions(-) diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index 1de41690..8729723 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -80,14 +80,6 @@ static __always_inline bool __preempt_count_dec_and_test(void) } /* - * Returns true when we need to resched -- even if we can not. - */ -static __always_inline bool need_resched(void) -{ - return unlikely(test_preempt_need_resched()); -} - -/* * Returns true when we need to resched and can (barring IRQ state). */ static __always_inline bool should_resched(void) diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h index 5dc14ed..ddf2b42 100644 --- a/include/asm-generic/preempt.h +++ b/include/asm-generic/preempt.h @@ -85,14 +85,6 @@ static __always_inline bool __preempt_count_dec_and_test(void) } /* - * Returns true when we need to resched -- even if we can not. - */ -static __always_inline bool need_resched(void) -{ - return unlikely(test_preempt_need_resched()); -} - -/* * Returns true when we need to resched and can (barring IRQ state). */ static __always_inline bool should_resched(void) diff --git a/include/linux/sched.h b/include/linux/sched.h index b09798b..2ac5285 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2577,6 +2577,11 @@ static inline bool __must_check current_clr_polling_and_test(void) } #endif +static __always_inline bool need_resched(void) +{ + return unlikely(tif_need_resched()); +} + /* * Thread group CPU time accounting. */