Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 20 Dec 2000 22:54:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 20 Dec 2000 22:54:14 -0500 Received: from linuxcare.com.au ([203.29.91.49]:11012 "EHLO front.linuxcare.com.au") by vger.kernel.org with ESMTP id ; Wed, 20 Dec 2000 22:53:56 -0500 From: Anton Blanchard Date: Thu, 21 Dec 2000 14:21:35 +1100 To: Heiko.Carstens@de.ibm.com Cc: Pavel Machek , Alan Cox , linux-kernel@vger.kernel.org Subject: Re: CPU attachent and detachment in a running Linux system Message-ID: <20001221142135.G6183@linuxcare.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from Heiko.Carstens@de.ibm.com on Mon, Dec 18, 2000 at 09:00:43AM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > That's a good point and it would probably work for attachment of cpus, but > it won't work for detachment because there are some data structures that > need to be updated if a cpu gets detached. For example it would be nice > to flush the per-cpu cache of the detached cpu in the slabcache. Then one > has to think of pending tasklets for the detached cpu which should be > moved to another cpu and then there are a lot of per-cpu data structures > in the networking part of the kernel.. most of them seem to be for > statistics only but I think these structures should be updated in any > case. > So at least for detaching it would make sense to register functions which > will be called whenever a cpu gets detached. I remember someone from SGI had a patch to merge all the per cpu structures together which would make this easier. It would also save bytes especially on machines like the e10k where we must have NR_CPUS = 64. Anton - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/