Messages in this thread | | | Date | Mon, 6 Jul 2009 08:47:19 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: + memory-hotplug-alloc-page-from-other-node-in-memory-online.patch added to -mm tree |
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On Fri, 3 Jul 2009 17:12:06 +0800 Shaohua Li <shaohua.li@intel.com> wrote:
> On Fri, Jul 03, 2009 at 07:55:56AM +0800, KAMEZAWA Hiroyuki wrote: > > On Thu, 2 Jul 2009 09:31:04 -0400 (EDT) > > Christoph Lameter <cl@linux-foundation.org> wrote: > > > > > On Thu, 2 Jul 2009, Yasunori Goto wrote: > > > > > > > However, I don't enough time for memory hotplug now, > > > > and they are just redundant functions now. > > > > If someone create new allocator (and unifying bootmem allocator), > > > > I'm very glad. :-) > > > > > > "Senior"ities all around.... A move like that would require serious > > > commitment of time. None of us older developers can take that on it > > > seems. > > > > > > Do we need to accept that the zone and page metadata are living on another > > > node? > > > > > I don't think so. Someone should do. I just think I can't do it _now_. > > (because I have more things to do for cgroup..) > > > > And, if not node-hotplug, memmap is allocated from local memory if possible. > > "We should _never_ allow fallback to other nodes or not" is problem ? > > I think we should allow fallback. > > About pgdat, zones, I hope they will be on-cache... > > > > Maybe followings are necessary for allocating pgdat/zones from local node > > at node-hotplug. > > > > a) Add new tiny functions to alloacate memory from not-initialized area. > > allocate pgdat/memmap from here if necessary. > > b) leave allocated memory from (a) as PG_reserved at onlining. > > c) There will be "not unpluggable" section after (b). We should show this to > > users. > > d) For removal, we have to keep precise trace of PG_reserved pages. > > e) vmemmap removal, which uses large page for vmemmap, is a problem. > > edges of section memmap is not aligned to large pages. Then we need > > some clever trick to handle this. > > > > Allocationg memmap from its own section was an idea (I love this) but > > IBM's 16MB memory section doesn't allow this. > Adding code for allocation should not be hard, but hard to make the memory > unpluggable. For example, the vmemmap page table pages can map several > sections and even several nodes (a pgd page). This will make some sections > completely not unpluggable if the sections have page table pages. > Is it possible we can merge the workaround temporarily? Without it, the hotplug > fails immediately in our side. > ZONE_MOVABLE is for that. I wonder current ZONE_MOVABLE interface is not enough. If section should be removable later, the section should be onlined as ZONE_MOVABLE as following.
example) echo removable_online > /sys/devices/system/memory/memoryXXX/online
thx, -Kame
> Thanks, > Shaohua > > -- > 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> >
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