Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx> writes: > On Mon, Sep 19, 2016 at 11:59:35AM +0530, Aneesh Kumar K.V wrote: >>Movable node also does. >> memblock_set_bottom_up(true); >>What is the impact of that. Do we need changes equivalent to that ? Also >>where are we marking the nodes which can be hotplugged, ie where do we >>do memblock_mark_hotplug() ? > > These are related to the mechanism x86 uses to create movable nodes at > boot. The SRAT is parsed to mark any hotplug memory. That marking is > used later when initializing ZONE_MOVABLE for each node. [1] > > The bottom-up allocation is due to a timing issue [2]. There is a window > where kernel memory may be allocated before the SRAT is parsed. Any > bottom-up allocations done during that time will likely be in the same > (nonmovable) node as the kernel image. > > On power, I don't think we have a heuristic equivalent to that SRAT > memory hotplug info. So, we'll be limited to dynamically adding movable > nodes after boot. > > 1. http://events.linuxfoundation.org/sites/events/files/lcjp13_chen.pdf > 2. commit 79442ed189ac ("mm/memblock.c: introduce bottom-up allocation > mode") > What I was checking was how will one mark a node movable in ppc64 ? I don't see ppc64 code doing the equivalent of memblock_mark_hotplug(). So when you say "Onlining memory into ZONE_MOVABLE requires CONFIG_MOVABLE_NODE" where is that restriction ?. IIUC, should_add_memory_movable() will only return ZONE_MOVABLE only if it is non empty and MOVABLE_NODE will create a ZONE_MOVABLE zone by default only if it finds a memblock marked hotpluggable. So wondering if we are not calling memblock_mark_hotplug() how is it working. Or am I missing something ? -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>