Hi Tang,
On Thu, 2013-01-31 at 11:31 +0800, Tang Chen wrote:
> Hi Simon,
>
> Please see below. :)
>
> On 01/31/2013 09:22 AM, Simon Jeons wrote:
> >
> > Sorry, I still confuse. :(
> > update node_states[N_NORMAL_MEMORY] to node_states[N_MEMORY] or
> > node_states[N_NORMAL_MEMOR] present 0...ZONE_MOVABLE?
> >
> > node_states is what? node_states[N_NORMAL_MEMOR] or
> > node_states[N_MEMORY]?
>
> Are you asking what node_states[] is ?
>
> node_states[] is an array of nodemask,
>
> extern nodemask_t node_states[NR_NODE_STATES];
>
> For example, node_states[N_NORMAL_MEMOR] represents which nodes have
> normal memory.
> If N_MEMORY == N_HIGH_MEMORY == N_NORMAL_MEMORY, node_states[N_MEMORY] is
> node_states[N_NORMAL_MEMOR]. So it represents which nodes have 0 ...
> ZONE_MOVABLE.
>
Sorry, how can nodes_state[N_NORMAL_MEMORY] represents a node have 0 ...
*ZONE_MOVABLE*, the comment of enum nodes_states said that
N_NORMAL_MEMORY just means the node has regular memory.
>
> > Why check !z1->wait_table in function move_pfn_range_left and function
> > __add_zone? I think zone->wait_table is initialized in
> > free_area_init_core, which will be called during system initialization
> > and hotadd_new_pgdat path.
>
> I think,
>
> free_area_init_core(), in the for loop,
> |--> size = zone_spanned_pages_in_node();
> |--> if (!size)
> continue; ---------------- If zone is empty, we jump
> out the for loop.
> |--> init_currently_empty_zone()
>
> So, if the zone is empty, wait_table is not initialized.
>
> In move_pfn_range_left(z1, z2), we move pages from z2 to z1. But z1
> could be empty.
> So we need to check it and initialize z1->wait_table because we are
> moving pages into it.
thanks.
>
>
> > There is a zone populated check in function online_pages. But zone is
> > populated in free_area_init_core which will be called during system
> > initialization and hotadd_new_pgdat path. Why still need this check?
> >
>
> Because we could also rebuild zone list when we offline pages.
>
> __offline_pages()
> |--> zone->present_pages -= offlined_pages;
> |--> if (!populated_zone(zone)) {
> build_all_zonelists(NULL, NULL);
> }
>
> If the zone is empty, and other zones on the same node is not empty, the
> node
> won't be offlined, and next time we online pages of this zone, the pgdat
> won't
> be initialized again, and we need to check populated_zone(zone) when
> onlining
> pages.
thanks.
>
> Thanks. :)
>
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