From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756608Ab0CKKDm (ORCPT ); Thu, 11 Mar 2010 05:03:42 -0500 Received: from mail.gmx.net ([213.165.64.20]:54108 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756420Ab0CKKDk (ORCPT ); Thu, 11 Mar 2010 05:03:40 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX18RzER+oXsRBLOE+K0nfv1Ol9Vp6mxazM7Y7Z0EqY 31+Wtt/y99S7Ru Subject: Re: [patch 10/12] sched: remove SYNC_WAKEUPS feature From: Mike Galbraith To: Peter Zijlstra Cc: Ingo Molnar , LKML In-Reply-To: <1268300950.6785.27.camel@marge.simson.net> References: <1268300950.6785.27.camel@marge.simson.net> Content-Type: text/plain Date: Thu, 11 Mar 2010 11:03:37 +0100 Message-Id: <1268301817.6785.47.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sched: remove SYNC_WAKEUPS feature Sync wakeups are critical functionality with a long history. Remove it, we don't need the branch or icache footprint. Signed-off-by: Mike Galbraith Cc: Ingo Molnar Cc: Peter Zijlstra LKML-Reference: --- kernel/sched.c | 3 --- kernel/sched_features.h | 8 -------- 2 files changed, 11 deletions(-) Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -2369,9 +2369,6 @@ static int try_to_wake_up(struct task_st unsigned long flags; struct rq *rq, *orig_rq; - if (!sched_feat(SYNC_WAKEUPS)) - wake_flags &= ~WF_SYNC; - this_cpu = get_cpu(); smp_wmb(); Index: linux-2.6/kernel/sched_features.h =================================================================== --- linux-2.6.orig/kernel/sched_features.h +++ linux-2.6/kernel/sched_features.h @@ -17,14 +17,6 @@ SCHED_FEAT(START_DEBIT, 1) SCHED_FEAT(WAKEUP_PREEMPT, 1) /* - * Use the SYNC wakeup hint, pipes and the likes use this to indicate - * the remote end is likely to consume the data we just wrote, and - * therefore has cache benefit from being placed on the same cpu, see - * also AFFINE_WAKEUPS. - */ -SCHED_FEAT(SYNC_WAKEUPS, 1) - -/* * Based on load and program behaviour, see if it makes sense to place * a newly woken task on the same cpu as the task that woke it -- * improve cache locality. Typically used with SYNC wakeups as