From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751762AbXEBI0v (ORCPT ); Wed, 2 May 2007 04:26:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753423AbXEBI0v (ORCPT ); Wed, 2 May 2007 04:26:51 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:60961 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751762AbXEBI0u (ORCPT ); Wed, 2 May 2007 04:26:50 -0400 Date: Wed, 2 May 2007 01:26:47 -0700 From: Paul Jackson To: David Rientjes Cc: torvalds@linux-foundation.org, menage@google.com, clameter@cthulhu.engr.sgi.com, linux-kernel@vger.kernel.org Subject: Re: [patch] cpusets: allow empty {cpus,mems}_allowed to be set for unpopulated cpuset Message-Id: <20070502012647.fbc0d502.pj@sgi.com> In-Reply-To: References: Organization: SGI X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.3; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Other than the detail of allowing a newline from doing: echo > cpus to work, I'm ok with this patch. It passes my cpuset_test, and seems to allow unpopulating cpusets, as advertised. Aha - as I was writing this, I noticed that the command: echo -n '' > cpus does -not- work! The echo command recognizes that as a write of zero non-null bytes, and skips the write altogether. We have to add the code to handle an input line consisting of just a bare newline, to mean an empty mask. Well, we don't -have- to. But writing a single nul byte in shell script will challenge most shell script hackers. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401