From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751528AbWCIVHj (ORCPT ); Thu, 9 Mar 2006 16:07:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751542AbWCIVHj (ORCPT ); Thu, 9 Mar 2006 16:07:39 -0500 Received: from a34-mta02.direcpc.com ([66.82.4.91]:36057 "EHLO a34-mta02.direcway.com") by vger.kernel.org with ESMTP id S1751528AbWCIVHi (ORCPT ); Thu, 9 Mar 2006 16:07:38 -0500 Date: Thu, 09 Mar 2006 16:06:47 -0500 From: Ben Collins Subject: SMP on UP (Was Re: State of the Linux PCI and PCI Hotplug Subsystems for 2.6.16-rc5) In-reply-to: <1141937556.13319.64.camel@mindpipe> To: Lee Revell Cc: Linux Kernel Mailing List Message-id: <1141938407.4406.4.camel@grayson> Organization: Ubuntu MIME-version: 1.0 X-Mailer: Evolution 2.5.92 Content-type: text/plain Content-transfer-encoding: 7BIT References: <20060306223545.GA20885@kroah.com> <20060308222652.GR4006@stusta.de> <20060308225029.GA26117@suse.de> <20060308231851.GA26666@suse.de> <20060309184010.GA4639@irc.pl> <1141935002.6072.40.camel@grayson> <1141937556.13319.64.camel@mindpipe> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2006-03-09 at 15:52 -0500, Lee Revell wrote: > On Thu, 2006-03-09 at 15:10 -0500, Ben Collins wrote: > > The difference between our 2.6.15 386 and 686 kernels is actually pretty > > huge. The 386 is M486, and UP, while our 686 kernel is M686, and SMP. > > The SMP is also complicated by our use of the SMP-alternatives patch, > > but I believe I had this user test with this disabled (kernel command > > line option that leaves all the SMP code intact for testing). It didn't > > alter the problem. > > Ubuntu doesn't provide a UP 686 kernel? > > Isn't there a performance hit running an SMP kernel on UP? This is a little off-topic to the original thread, so trimming CC and changing subject. As mentioned above, we have the SMP-alternatives patch, which will basically convert SMP related code (lock op's and some atomic operations) to UP, on-the-fly (at boot for the kernel, and at load for modules). It's not 100% the same as running a UP kernel, but it comes close enough that it allows us to distribute fewer kernels. This equates to less load on us and our users. I don't want to start this whole thread over again, so check back in the linux-kernel archives for the SMP alternatives patch thread. -- Ubuntu - http://www.ubuntu.com/ Debian - http://www.debian.org/ Linux 1394 - http://www.linux1394.org/ SwissDisk - http://www.swissdisk.com/