Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1163349AbWLGVHN (ORCPT ); Thu, 7 Dec 2006 16:07:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1163350AbWLGVHN (ORCPT ); Thu, 7 Dec 2006 16:07:13 -0500 Received: from hancock.steeleye.com ([71.30.118.248]:46298 "EHLO hancock.sc.steeleye.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1163348AbWLGVHK (ORCPT ); Thu, 7 Dec 2006 16:07:10 -0500 Subject: Re: [PATCH 3/3] WorkStruct: Use direct assignment rather than cmpxchg() From: James Bottomley To: David Howells Cc: Andrew Morton , torvalds@osdl.org, davem@davemloft.com, wli@holomorphy.com, matthew@wil.cx, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org In-Reply-To: <639.1165521999@redhat.com> References: <20061207085409.228016a2.akpm@osdl.org> <20061207153138.28408.94099.stgit@warthog.cambridge.redhat.com> <20061207153143.28408.7274.stgit@warthog.cambridge.redhat.com> <639.1165521999@redhat.com> Content-Type: text/plain Date: Thu, 07 Dec 2006 15:06:37 -0600 Message-Id: <1165525597.4698.46.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 X-Mailer: Evolution 2.6.3 (2.6.3-1.fc5.5) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 830 Lines: 19 On Thu, 2006-12-07 at 20:06 +0000, David Howells wrote: > Remember: if you have to put a conditional jump in there, it's going to fail > one way or the other a certain percentage of the time, and that's going to > cause a pipeline stall, and these ops are used quite a lot. That we'd have to put a conditional jump in there is an incorrect assumption on risc machines. At least on parisc we can do conditional nullifies in the executing instruction pipeline, so we'd read, nullify the following write if the bit were set. We do this a lot in our page interruption handlers. James - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/