From: Pavel Machek Subject: Re: [PATCH 1/1] x86: fix text_poke Date: Fri, 25 Apr 2008 20:53:50 +0200 Message-ID: <20080425185350.GA2679@elf.ucw.cz> References: <20080425.021301.193689806.davem@davemloft.net> <1209343883-7991-1-git-send-email-jirislaby@gmail.com> <20080425151931.GA25510@elte.hu> <20080425152650.GA894@elte.hu> <20080425155000.GA4438@elte.hu> <4811FF60.6040905@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ingo Molnar , Linus Torvalds , Jiri Slaby , David Miller , zdenek.kabelac@gmail.com, rjw@sisk.pl, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org, linux-ext4@vger.kernel.org, herbert@gondor.apana.org.au, penberg@cs.helsinki.fi, clameter@sgi.com, linux-kernel@vger.kernel.org, Mathieu Desnoyers , Andi Kleen , pageexec@freemail.hu, Jeremy Fitzhardinge To: "H. Peter Anvin" Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:54886 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933195AbYDYSxK (ORCPT ); Fri, 25 Apr 2008 14:53:10 -0400 Content-Disposition: inline In-Reply-To: <4811FF60.6040905@zytor.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri 2008-04-25 08:57:20, H. Peter Anvin wrote: > Ingo Molnar wrote: >> >> text_poke() itself only applies/unapplies the LOCK prefix - a single byte. >> We shouldnt be doing that at all: the cost of LOCK is insignificant (a few >> cycles) and most systems are SMP anyway. >> > > Alas, on older CPUs the cost of LOCK can be massive. The question is how > much we really care - the embedded people (who would definitely be > affected) will simply build UP kernels, and this only affects booting SMP > kernels on UP. Like... say distros on older hardware? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html