From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757946Ab1EaRoh (ORCPT ); Tue, 31 May 2011 13:44:37 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:34577 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757546Ab1EaRog (ORCPT ); Tue, 31 May 2011 13:44:36 -0400 Date: Tue, 31 May 2011 10:44:30 -0700 From: "Paul E. McKenney" To: Linus Torvalds Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , Andrew Morton Subject: Re: [GIT PULL] RCU fix Message-ID: <20110531174430.GG2393@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20110531162726.GA15162@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 01, 2011 at 02:05:21AM +0900, Linus Torvalds wrote: > On Wed, Jun 1, 2011 at 1:27 AM, Ingo Molnar wrote: > > > > Please pull the latest core-urgent-for-linus git tree from: > > > >   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git core-urgent-for-linus > > So remind me again why RCU switched to the stupid threads? It caused > problems for rcutiny, it now causes silly problems for rcutree. Why do > it? It's just extra complexity and no real advantage afaik. The reason for the switch is to allow threads blocked in TREE_PREEMPT_RCU and TINY_PREEMPT_RCU RCU read-side critical sections to have their priority boosted in order to avoid OOM. People have made these OOMs happen, so this is not longer just a theoretical concern. Thanx, Paul