From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034457AbcIVSmq (ORCPT ); Thu, 22 Sep 2016 14:42:46 -0400 Received: from merlin.infradead.org ([205.233.59.134]:46066 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030254AbcIVSmm (ORCPT ); Thu, 22 Sep 2016 14:42:42 -0400 Date: Thu, 22 Sep 2016 20:42:28 +0200 From: Peter Zijlstra To: Mikulas Patocka Cc: hpa@zytor.com, paulmck@linux.vnet.ibm.com, josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, torvalds@linux-foundation.org, mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, oleg@redhat.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:sched/core] sched/core: Avoid _cond_resched() for PREEMPT=y Message-ID: <20160922184228.GA5012@twins.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 22, 2016 at 02:25:01PM -0400, Mikulas Patocka wrote: > I've found a document that says that cond_resched() is needed on > preemptible kernels to mark RCU quiescent states: > > https://lwn.net/Articles/603252/ > > Paul, is cond_resched() still needed on current RCU implementation? Or not? No, we ripped that out. See 4a81e8328d37 ("rcu: Reduce overhead of cond_resched() checks for RCU")