Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932163Ab0FYQFo (ORCPT ); Fri, 25 Jun 2010 12:05:44 -0400 Received: from nlpi129.sbcis.sbc.com ([207.115.36.143]:58466 "EHLO nlpi129.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364Ab0FYQFn (ORCPT ); Fri, 25 Jun 2010 12:05:43 -0400 Date: Fri, 25 Jun 2010 11:00:25 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@router.home To: Rusty Russell cc: Ingo Molnar , linux-kernel@vger.kernel.org, Russell King , Bryan Wu , Tony Luck , Ralf Baechle , Benjamin Herrenschmidt , Paul Mundt , "David S. Miller" , Arnd Bergmann , anton@samba.org, KOSAKI Motohiro , Mike Travis , Bryan Wu , Tony Luck , Ralf Baechle , Benjamin Herrenschmidt , Paul Mundt , "David S. Miller" , Arnd Bergmann , anton@samba.org, KOSAKI Motohiro , Mike Travis Subject: Re: [PATCH 2/5] cpumask: make task_struct.cpus_allowed a cpumask_var_t In-Reply-To: <201006252233.40481.rusty@rustcorp.com.au> Message-ID: References: <201006252233.40481.rusty@rustcorp.com.au> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 689 Lines: 17 On Fri, 25 Jun 2010, Rusty Russell wrote: > Even better would be to point to the fixed "one cpu" and "all cpus" > masks where possible, and make a copy when setting it to something > else. But you'd have to track down those naughty places which frob it > directly... Put it into a read only segment? What is the estimated performance impact of adding a level of indirection (and a potential cache miss) to a number of critical code paths? -- 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/