From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759268AbYE0QNA (ORCPT ); Tue, 27 May 2008 12:13:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758869AbYE0QMM (ORCPT ); Tue, 27 May 2008 12:12:12 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:46867 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758863AbYE0QML (ORCPT ); Tue, 27 May 2008 12:12:11 -0400 Date: Tue, 27 May 2008 09:11:33 -0700 (PDT) From: Linus Torvalds To: "Paul E. McKenney" cc: Oleg Nesterov , Alexey Dobriyan , Linux Kernel Mailing List , Andrew Morton Subject: Re: 2.6.26-rc4: RIP find_pid_ns+0x6b/0xa0 In-Reply-To: <20080527154001.GB14296@linux.vnet.ibm.com> Message-ID: References: <20080527052318.GA28301@martell.zuzino.mipt.ru> <20080527090605.GA146@tv-sign.ru> <20080527154001.GB14296@linux.vnet.ibm.com> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 27 May 2008, Paul E. McKenney wrote: > > But this will only help until preemptible spinlocks arrive, right? I don't think we will ever have preemptible spinlocks. If you preempt spinlocks, you have serious issues with contention and priority inversion etc, and you basically need to turn them into sleeping mutexes. So now you also need to do interrupts as sleepable threads etc etc. And it would break the existing non-preempt RCU usage anyway. Yeah, maybe the RT people try to do that, but quite frankly, it is insane. Spinlocks are *different* from sleeping locks, for a damn good reason. Linus