Messages in this thread | | | Date | Thu, 31 Jan 2013 15:10:50 +0800 | From | Tang Chen <> | Subject | Re: [PATCH v6 00/15] memory-hotplug: hot-remove physical memory |
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On 01/31/2013 02:19 PM, Simon Jeons wrote: > 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. >
Hi Simon,
Let's say it in this way.
If we don't have CONFIG_HIGHMEM, N_HIGH_MEMORY == N_NORMAL_MEMORY. We don't have a separate macro to represent highmem because we don't have highmem. This is easy to understand, right ?
Now, think it just like above: If we don't have CONFIG_MOVABLE_NODE, N_MEMORY == N_HIGH_MEMORY == N_NORMAL_MEMORY. This means we don't allow a node to have only movable memory, not we don't have movable memory. A node could have normal memory and movable memory. So nodes_state[N_NORMAL_MEMORY] represents a node have 0 ... *ZONE_MOVABLE*.
I think the point is: CONFIG_MOVABLE_NODE means we allow a node to have only movable memory. So without CONFIG_MOVABLE_NODE, it doesn't mean a node cannot have movable memory. It means the node cannot have only movable memory. It can have normal memory and movable memory.
1) With CONFIG_MOVABLE_NODE: N_NORMAL_MEMORY: nodes who have normal memory. normal memory only normal and highmem normal and highmem and movablemem normal and movablemem N_MEMORY: nodes who has memory (any memory) normal memory only normal and highmem normal and highmem and movablemem normal and movablemem ---------------- We can have movablemem. highmem only ------------------------- highmem and movablemem --------------- movablemem only ---------------------- We can have movablemem only. ***
2) With out CONFIG_MOVABLE_NODE: N_MEMORY == N_NORMAL_MEMORY: (Here, I omit N_HIGH_MEMORY) normal memory only normal and highmem normal and highmem and movablemem normal and movablemem ---------------- We can have movablemem. No movablemem only ------------------- We cannot have movablemem only. ***
The semantics is not that clear here. So we can only try to understand it from the code where we use N_MEMORY. :)
That is my understanding of this.
Thanks. :)
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