From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754876AbYLBXJs (ORCPT ); Tue, 2 Dec 2008 18:09:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752960AbYLBXJk (ORCPT ); Tue, 2 Dec 2008 18:09:40 -0500 Received: from ozlabs.org ([203.10.76.45]:34098 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752943AbYLBXJk (ORCPT ); Tue, 2 Dec 2008 18:09:40 -0500 From: Rusty Russell To: Andrew Morton Subject: Re: [PATCH 3/5] ring-buffer: read page interface Date: Wed, 3 Dec 2008 09:39:29 +1030 User-Agent: KMail/1.10.1 (Linux/2.6.27-9-generic; KDE/4.1.2; i686; ; ) Cc: Steven Rostedt , linux-kernel@vger.kernel.org, mingo@elte.hu, fweisbec@gmail.com, srostedt@redhat.com References: <20081202203404.496794864@goodmis.org> <20081202203425.040910271@goodmis.org> <20081202133654.2dfa51cd.akpm@linux-foundation.org> In-Reply-To: <20081202133654.2dfa51cd.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200812030939.29907.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 03 December 2008 08:06:54 Andrew Morton wrote: > Steven Rostedt wrote: > > + if (!local_read(&cpu_buffer->reader_page->page->commit)) > > Rusty (I think it was Rusty) has convincingly argued that local_t is > irredeemably busted. I forget the details? That was probably Christoph Lameter. The x86 implementation needs some love, but the API seems reasonable. On x86-32, the cpu_local_inc should be (as intended) turned into one insn. That would be possible on 64 bit once we get zero-based percpu (as will World Peace). Cheers, Rusty.