From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [patch 3/4] cpu alloc: The allocator Date: Mon, 6 Oct 2008 07:10:43 +1000 References: <20080929193500.470295078@quilx.com> <20081003003342.4d592c1f.akpm@linux-foundation.org> <48E614A0.60209@linux-foundation.org> In-Reply-To: <48E614A0.60209@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200810060810.43511.rusty@rustcorp.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, jeremy@goop.org, ebiederm@xmission.com, travis@sgi.com, herbert@gondor.apana.org.au, xemul@openvz.org, penberg@cs.helsinki.fi List-ID: On Friday 03 October 2008 22:48:32 Christoph Lameter wrote: > Andrew Morton wrote: > > But I'd have though that it would be possible to only allocate the > > storage for online CPUs. That would be a pretty significant win for > > some system configurations? > > We have tried that but currently the kernel (core and in particular arch > code) keeps state for all possible cpus in percpu segments. Would require > more extensive cleanup of numerous arches to do. It shouldn't be a big win, since possible ~= online for most systems. And having all the per-cpu users register online and offline cpu callbacks is error prone and a PITA. Rusty. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org