From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Date: Mon, 21 Jul 2014 20:06:25 +0000 Subject: Re: [RFC Patch V1 00/30] Enable memoryless node on x86 platforms Message-Id: <20140721200625.GR3935@laptop> List-Id: References: <1405064267-11678-1-git-send-email-jiang.liu@linux.intel.com> <20140721172331.GB4156@linux.vnet.ibm.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tony Luck Cc: Nishanth Aravamudan , Jiang Liu , Andrew Morton , Mel Gorman , David Rientjes , Mike Galbraith , "Rafael J . Wysocki" , "linux-mm@kvack.org" , linux-hotplug@vger.kernel.org, Linux Kernel Mailing List On Mon, Jul 21, 2014 at 10:41:59AM -0700, Tony Luck wrote: > On Mon, Jul 21, 2014 at 10:23 AM, Nishanth Aravamudan > wrote: > > It seems like the issue is the order of onlining of resources on a > > specific x86 platform? > > Yes. When we online a node the BIOS hits us with some ACPI hotplug events: > > First: Here are some new cpus > Next: Here is some new memory > Last; Here are some new I/O things (PCIe root ports, PCIe devices, > IOAPICs, IOMMUs, ...) > > So there is a period where the node is memoryless - although that will generally > be resolved when the memory hot plug event arrives ... that isn't guaranteed to > occur (there might not be any memory on the node, or what memory there is > may have failed self-test and been disabled). Right, but we could 'easily' capture that in arch code and make it look like it was done in a 'sane' order. No need to wreck the rest of the kernel to support this particular BIOS fuckup.