Messages in this thread | | | Date | Sat, 23 Jun 2012 15:35:37 -0700 | Subject | Re: [patch 046/181] mm: remove sparsemem allocation details from the bootmem allocator | From | Yinghai Lu <> |
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On Sat, Jun 23, 2012 at 3:06 PM, Johannes Weiner <hannes@cmpxchg.org> wrote: > On Sat, Jun 23, 2012 at 11:58:02AM -0700, Yinghai Lu wrote: >> +again: >> + p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size, >> + SMP_CACHE_BYTES, goal, limit); >> + if (!p && limit) { >> + limit = 0; >> + goto again; >> + } > > I was aware that __alloc_bootmem_node_nopanic does a slightly > different fallback sequence, but as soon as you go outside the > section, you have a node-section-dependency either way.
you need to make sure, first try to get the in the same section, then same node.
> > Without this patch, it would retry without the node first, then > without the goal. With your patch, you would try to limit the upper > end, but you may already go below the requested section. What would > the limit gain?
goal: start of section limit: start of next section.
the layout should be start_of_range_same_node...start_of_range_same_section....end_of_range_same_section...end_of_range_of_same_node.
before your commit: 1. first try: start_of_range_same_section....end_of_range_same_section 2. second try: on same node.
with your commit: 1. first try: start_of_range_same_section....end_of_range_same_node. ===> it would get buffer out of same section. 2. second try: 0...0, aka 0... -1UL
with this patch: 1. first try: start_of_range_same_section....end_of_range_same_section 2. second try: 0...end_of_range_of_same_section. 3. third try: start_of_range_same_section...0, aka tart_of_range_same_section...-1UL; 4. third try: 0...0, aka 0...-1UL;
Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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