Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755165Ab1C3Azi (ORCPT ); Tue, 29 Mar 2011 20:55:38 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:55098 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753849Ab1C3Azh (ORCPT ); Tue, 29 Mar 2011 20:55:37 -0400 Date: Tue, 29 Mar 2011 17:56:14 -0700 From: Andrew Morton To: Mike Travis Cc: Thomas Gleixner , Jack Steiner , Lee Schermerhorn , Andy Shevchenko , LKML Subject: Re: [PATCH] bitmap, irq: Add smp_affinity_list interface to /proc/irq Message-Id: <20110329175614.0c41ae8c.akpm@linux-foundation.org> In-Reply-To: <4D927E86.90400@sgi.com> References: <4D926F6C.8010705@sgi.com> <20110329165612.bd6ad7e4.akpm@linux-foundation.org> <20110329174314.80cf7b50.akpm@linux-foundation.org> <4D927E86.90400@sgi.com> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1784 Lines: 47 On Tue, 29 Mar 2011 17:51:18 -0700 Mike Travis wrote: > > > > Also, the patch adds a new interface which duplicates an existing one, > > only the formats are different, yes? This is, of course, bad. > > > > The only justification we've seen for being bad is "Manually adjusting > > the smp_affinity for IRQ's becomes unwieldy when the cpu count is > > large". A more thorough description of how painful this is might help > > motivate people to do bad things to the kernel. > > > > Also, if it's just a matter of an alternative presentation of the data, > > why not implement the desired user interface with a little userspace > > tool then feed the results down into the existing kernel interface? > > > > Setting smp affinity to cpus 256 to 263 would be: > > echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity > > instead of: > > echo 256-263 > smp_affinity_list > > Think about what it looks like for cpus around say, 4088 to 4095. > > We already have many alternate "list" interfaces: > > /sys/devices/system/cpu/cpuX/indexY/shared_cpu_list > /sys/devices/system/cpu/cpuX/topology/thread_siblings_list > /sys/devices/system/cpu/cpuX/topology/core_siblings_list > /sys/devices/system/node/nodeX/cpulist > /sys/devices/pci***/***/local_cpulist > > etc. > > This just expands on that same philosophy. You mean that if someone had written a stupid little tool to convert a list of tuples into a bitmap, we wouldn't have needed to add all that crap to the kernel? -- 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/