From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756457AbbJANZv (ORCPT ); Thu, 1 Oct 2015 09:25:51 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:35700 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752764AbbJANZs (ORCPT ); Thu, 1 Oct 2015 09:25:48 -0400 Date: Thu, 1 Oct 2015 15:25:46 +0200 From: Frederic Weisbecker To: Peter Zijlstra Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, oleg@redhat.com, umgwanakikbuti@gmail.com, tglx@linutronix.de, rostedt@goodmis.org Subject: Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT Message-ID: <20151001132546.GF3432@lerouge> References: <20150930071035.514587432@infradead.org> <20150930072303.631400497@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150930072303.631400497@infradead.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 30, 2015 at 09:10:36AM +0200, Peter Zijlstra wrote: > As per commit d86ee4809d03 ("sched: optimize cond_resched()") we need > PREEMPT_ACTIVE to avoid cond_resched() from working before the > scheduler is setup. > > However, keeping preemption disabled should do the same thing already, > making the PREEMPT_ACTIVE part entirely redundant. > > The only complication is !PREEMPT_COUNT kernels, where > PREEMPT_DISABLED ends up being 0. Instead we use an unconditional > PREEMPT_OFFSET to set preempt_count() even on !PREEMPT_COUNT kernels. > > Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Frederic Weisbecker