Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030216AbWCWIhK (ORCPT ); Thu, 23 Mar 2006 03:37:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030217AbWCWIhK (ORCPT ); Thu, 23 Mar 2006 03:37:10 -0500 Received: from mx.pathscale.com ([64.160.42.68]:11916 "EHLO mx.pathscale.com") by vger.kernel.org with ESMTP id S1030216AbWCWIhI (ORCPT ); Thu, 23 Mar 2006 03:37:08 -0500 Subject: Re: [PATCH 10 of 18] ipath - support for userspace apps using core driver From: "Bryan O'Sullivan" To: Andrew Morton Cc: linux-kernel@vger.kernel.org, rdreier@cisco.com, greg@kroah.com, openib-general@openib.org In-Reply-To: <20060322190636.667d43c0.akpm@osdl.org> References: <35c1d2f22ae1e2de483c.1143072303@eng-12.pathscale.com> <20060322190636.667d43c0.akpm@osdl.org> Content-Type: text/plain Date: Thu, 23 Mar 2006 00:37:07 -0800 Message-Id: <1143103027.6411.9.camel@camp4.serpentine.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 874 Lines: 23 On Wed, 2006-03-22 at 19:06 -0800, Andrew Morton wrote: > CPU topology is available in sysfs - it shouild be possible to push policy > decisions like this up to userspace. We covered this in an earlier round of submission, but I should have updated the inline comments. While we expose a way for userspace to open an explicit device based on its knowledge of topology, I think we need a "take your best shot" minor number, too, which is what this is. If we *don't* provide one, userspace can end up with exactly the kinds of messy race situations that used to be seen with ptys before /dev/ptmx and /dev/pts came along.